Simxpert R3.2 Crash Workspace Guide

Introduction 1

Crash Workspace Guide Introduction

2 Overview and Definition

Overview and Definition An overview of the SimXpert crash workspace is given here.

Introduction SimXpert crash is a preprocessor for graphically preparing input data for LS-DYNA, an explicit dynamic software, used in applications such as crash, crush, and drop test simulations. Use of crash workspace allows users to work within one common modeling environment with other SimXpert workspaces such as Structures. Thus, for example, a model originally prepared for NVH, linear, or implicit nonlinear analysis can be easily used in explicit applications (crash). This dramatically reduces the time spent to build different models for implicit and explicit analysis and prevents you from making mistakes because of unfamiliarity between different programs.

Theory A detailed theory of explicit analysis is outside the scope of this guide. However, it is important to understand the basics of the solution technique, since it is critical to many aspects of using the SimXpert crash workspace. If you are already familiar with explicit methods and how they differ from implicit methods, you may disregard this section.

Method of Solution Although crash simulation software, including LS-DYNA uses the Explicit methods, a brief overview of both the Implicit and the Explicit Methods for the solution of dynamic response calculations is given below. Implicit Methods Most finite element programs use implicit methods to carry out a transient solution. Normally, they use Newmark schemes to integrate in time. If the current time step is step acceleration at the end of step

n + 1 will satisfy the following equation of motion: ext

Ma' n + 1 + Cv' n + 1 + Kd' n + 1 = F n + 1 where:

M C K ext Fn + 1

n , a good estimate of the

=

mass matrix of the structure

=

damping matrix of the structure

=

stiffness matrix of the structure

=

vector of externally applied loads at step

n+1

Introduction 3 Overview and Definition

a' n + 1 v' n + 1 d' n + 1

n+1 = estimate of velocity at step n + 1 = estimate of displacement at step n + 1 =

estimate of acceleration at step

and the prime denotes an estimated value. The estimates of displacement and velocity are given by: 2

d'n + 1 = d n + v n Δt + ( ( 1 – 2β )a n Δt ) ⁄ 2 + βa'n + 1 Δt

2

v' n + 1 = v n + ( 1 – γ )a n Δt + γa'n + 1 Δt or

d'n + 1 = d *n + βa'n + 1 Δt

2

v' n + 1 = v n* + γa'n + 1 Δt where

Δt is the time step, and β , and γ are constants.

The terms

d n* and v n* are predictive and are based on values already calculated.

Substituting these values in the equation of motion results in 2

ext

Ma' n + 1 + C ( v* n + γa' n + 1 Δt ) + K ( d* n + βa' n + 1 Δt ) = F n + 1 or 2

ext

[ M + CγΔt + KβΔt ]a' n + 1 = F n + 1 – Cv n* – Kd n* The equation of motion may then be defined as residual

M*a'n + 1 = F n + 1

The accelerations are obtained by inverting the –1

M* matrix as follows:

residual

a'n + 1 = M* F n + 1

This is analogous to decomposing the stiffness matrix in a linear static analysis. However, in dynamics, mass and damping terms are also present.

4 Overview and Definition

Explicit Methods The equation of motion ext

Ma n + Cv n + Kd n = F n can be rewritten as ext

int

Ma n = F n – F n –1

residual

an = M Fn where:

ext

=

vector of externally applied loads

=

vector of internal loads (e.g., forces generated by the elements and hourglass forces)

=

Cv n + Kd n

=

mass matrix

Fn

int

Fn M

The acceleration can be found by inverting the mass matrix and multiplying it by the residual load vector. In LS_DYNA, like any explicit finite element code, the mass matrix is lumped which results in a diagonal mass matrix. Since M is diagonal, its inversion is trivial, and the matrix equation is a set of independent equations for each degree of freedom, as follows: residual

a ni = F ni

⁄ Mi

The Leap-frog scheme is used to advance in time. The position, forces, and accelerations are defined at time level n , while the velocities are defined at time level

n + 1 ⁄ 2 . Graphically, this can be depicted as:

v n + 1 ⁄ 2 = v n – 1 ⁄ 2 + a n ( Δt n + 1 ⁄ 2 + Δt n – 1 ⁄ 2 ) ⁄ 2 d n + 1 = dn + v n + 1 ⁄ 2 Δt n + 1 ⁄ 2

Introduction 5 Overview and Definition

n–1 d, F, a

n–1§2 v

n d, F , a

n+1§2

v

n+1 d, F , a

time

The Leap-frog scheme results in a central difference approximation for the acceleration, and is secondorder accurate in

Δt .

Explicit methods with a lumped mass matrix do not require matrix decompositions or matrix solutions. Instead, the loop is carried out for each time step as shown in the following diagram: Grid-Point Accelerations Leap-frog Integration in Time Grid-Point Velocities

Grid-Point Displacements

Element Formulation and Gradient Operator Element Stain Rates Constitutive Model and Integration Element Stresses Element Formulation and Divergence Operator Element Forces at Grid-Points CONTACT, Fluid-Structure Interaction, Force/Pressure boundaries + External Forces at Grid Points

Explicit Time Step Implicit methods can be made unconditionally stable regardless of the size of the time step. However, for explicit codes to remain stable, the time step must subdivide the shortest natural period in the mesh. This means that the time step must be less than the time taken for a stress wave to cross the smallest element in the mesh. Typically, explicit time steps are 100 to 1000 times smaller than those used with implicit codes. However, since each iteration does not involve the costly formulation and decomposition of matrices, explicit techniques are very competitive with implicit methods. Because the smallest element in an explicit solution determines the time step, it is extremely important to avoid very small elements in the mesh.

6 Overview and Definition

Courant Criterion Since it is impossible to do a complete eigenvalue analysis every cycle to calculate the timestep, an approximate method, known as the Courant Criterion, is used. This is based on the minimum time which is required for a stress wave to cross each element:

Δt = SL/c where:

Δt S L c

=

Timestep

=

Timestep scale factor (<1)

=

Smallest element dimension

=

Speed of sound in the element material

For 1-D elements, the speed of sound is defined as:

E⁄ρ

c = where:

E ρ

=

Young’s modulus

=

density

Implicit vs. Explicit Analysis The time step for implicit solutions can be much larger than is possible for explicit solutions. This makes implicit methods more attractive for transient events that occur over a long time period and are dominated by low frequency structural dynamics. Explicit solutions are better for short, transient events where the effects of stress waves are important. There is, of course, an area where either method is equally advantageous and may be used. Explicit solutions have a greater advantage over implicit solutions if the time step of the implicit solution has to be small for some reason. This may be necessary for problems that include: • Material nonlinearity. A high degree of material nonlinearity may require a small time step

for accuracy. • Large geometric nonlinearity. Contact and friction algorithms can introduce potential

instabilities, and a small time step may be needed for accuracy and stability. • Those analyses where the physics of the problem demands a small time step (e.g. stress wave

effects as in crash, crush, and impact analyses).

Introduction 7 Overview and Definition

• Material and geometric nonlinearity in combination with large displacements. Convergence

in implicit methods becomes more difficult to achieve as the amount of nonlinearity for all types increases.

Explicit Methods Have Increasing Advantages Over Implicit Methods as the Model Gets Bigger and Bigger.

8 Overview and Definition

Parts and Geometry 9

Parts and Geometry

10 Parts and Geometry

Parts and Geometry The geometry of the parts can be either created in SimXpert, or more likely imported from CAD program such as Catia, Pro/E.

Units SimXpert interprets all dimensions and input data with respect to a system of units. It is important to set the appropriate units prior to importing any unitless analysis files (such as a Nastran Bulk Data file) or creating materials, properties, or loads. You can control the system of units by selecting Units Manager from the Tools menu. If you import a file that contains units, SimXpert will convert them into those specified in the Units Manager.

Creating Geometry In the first release SimXpert has very limited geometry creation capabilities. It is possible to create curves and very simple surfaces. For the most part you will be importing geometry from an external source. The imported geometry can be edited in SimXpert

Importing Geometry If the geometry of the part is available in a CATIA, parasolid, IGES, or STL file, it can be directly imported into the SimXpert Crash Workspace.

Creating local coordinate systems Sometimes it is convenient to use local coordinate systems for specifying loads, and or boundary conditions. For example, a certain node may have a roller support placed in an inclined plane. A local

Parts and Geometry 11 Parts and Geometry

coordinate system with one of its axes normal to the inclined plane needs to be created and used to specify the fixity (SPC) of the displacement component along the direction normal to the inclined plane. CONSTRAINT

Local coordinate systems can be in cartesian, cylindrical or spherical systems. Coordinate system created in SimXpert are represented by the following icons, corresponding to the method selected. Spherical

Cylindrical

Cartesian

Coordinate System

Direction 1

Direction 2

Direction 3

1-3 plane

Cartesian

x

y

z

x-z (y=0)

Cylindrical

r

z

r-z ( θ =0)

Spherical

r

θ θ

φ

r- φ ( θ =0)

You can create local coordinate systems by selecting Cartesian, Cylindrical, or Spherical from the Coordinate System group under the Geometry tab. There are numerous methods to create local coordinate systems in SimXpert:

12 Parts and Geometry

1. 3 Points: Three points are used to define the coordinate system. The first point corresponds to the location of origin. The second point defines the point on a specified axis and the third point defines a point in a specified plane. 2. Euler: Creates a coordinate system through three specified rotations about the axes of an existing coordinate system. 3. Normal: Creates a coordinate system with its origin at a point location on a surface. A specified axis is normal to the surface. 4. Two Vectors: Creates a coordinate system with its origin at a designated location and two of the coordinate frame axes are defined using vectors 5. Advanced: Location and orientation can be independently defined. There are 4 different ways to define the location of the origin of the coordinate system: Geometry, Point/Node, Coordinate System, and Center of Part. Further, the orientation can also be defined 3 ways: Global, Two Axes, and Coordinate System.

Materials 13

Materials

14 Materials

Materials SimXpert Crash Workspace supports most of the LS-DYNA material types, covering isotropic, anisotropic, orthotropic, and laminated material properties. These material properties can be dependent on temperature, strain, and strain rate. Here we briefly describe all the material types supported currently by the crash workspace. Please refer to “LS-DYNA Keyword Users’ Manual”, for a full description of all the LS-DYNA supported materials.

Supported Materials MAT_ADD_EROSION This material model option provides a way of including failure in material models that do not allow failure and erosion. This option can also be applied to constitutive models with other failure and erosion criterion. Each of the criterion defined here is applied independently, and once any of them is satisfied, the element is deleted from further calculation.

Field

Comments

Title

Unique name identifying material model

Desc

Optional description of the material model

TITLE_OPTION

If selected material title option is used

MID

Material identification number (Integer > 0) for which this erosion definition applies.

EXCL

The Exclusion number. When any of the failure constants are set to the exclusion number, the associated failure criteria calculations are bypassed. For example, to prevent a material from going into tension, you may specify an unusual value for the exclusion number, e.g. 1234., set Pmin to 0.0 and all the remaining constants to 1234. The default value is 0.0, which eliminates all criteria from consideration that have their constants set to 0.0, or left blank.

PFAIL

Pressure at failure, Pmin. Failure occurs when pressure is less than PFAIL

Materials 15 Materials

Field

Comments

SIGP1

principal stress at failure, σmax. Failure occurs when the maximum principal stress exceeds SIGP1.

SIGVM

Equivalent stress at failure, σvM. Failure occurs when the von Mises equivalent stress exceeds SIGVM.

EPSP1

Principal strain at failure, εmax. Failure occurs when the maximum principal strain exceeds EPSP1.

EPSSH

Shear strain at failure, γmax. Failure occurs when the maximum shear strain exceeds EPSSH.

SIGTH

Threshold stress, σ0 (used in evaluating the Tuler-Butcher criterion)

IMPULSE

Stress impulse for failure, Kf. Failure occurs when the Tuler-Butcher criterion exceeds IMPULSE.

FAILTM

Failure time. When the analysis time exceeds the failure time, the material is removed.

Remarks: 1. This failure model only applies to the 2D and 3D solid elements with one point integration. See Also: • LS-DYNA Keyword User’s Manual MAT_ANISOTROPIC_ELASTIC This material model is used for modeling elastic anisotropic behavior of solids.

Field

Contents

Title

Unique name identifying the material model.

Desc

Optional description of the material model.

16 Materials

Field

Contents

TITLE_OPTION

If selected, the material Title will be exported to LS-DYNA

MID

Material identification number. (Integer > 0)

RO

Mass density.

C11... C66

Anisotropic constitutive matrix components

AOPT

Material axes option

XP, YP, ZP

Coordinates for point P (for AOPT= 1 and 4)

A1, A2, A3

Components of a vector a (for AOPT=2)

D1, D2, D3

Components of a vector d (for AOPT=2)

V1, V2, V3

Components of a vector v (for AOPT= 3 and 4)

BETA

Material angle in degrees (for AOPT= 3)

REF

Use Reference geometry to initialize the stress tensor

See Also: • LS-DYNA Keyword User’s Manual MAT_BLATZ-KO_RUBBER This is used to model nearly incompressible continuum rubber. The Poisson’s ratio is fixed to 0.463

Field

Comments

Title

Unique name identifying material model

Desc

Optional description of the material model

TITLE_OPTION

If selected material title option is used

MID

Material identification number (Integer > 0)

RO

Mass Density of the material

G

Shear modulus

REF

Use reference geometry to initialize the stress tensor (0 =off; 1 = on)

See Also: • LS-DYNA Keyword User’s Manual

Materials 17 Materials

MAT_CABLE_DISCRETE_BEAM This material model is used to define elastic cables realistically.

Field

Comments

Title

Unique name identifying material model

Desc

Optional description of the material model

TITLE_OPTION

If selected material title option is used

MID

Material identification number (Integer > 0)

RO

Mass density

E

Young’s modulus (if value greater than zero), or stiffness (if value smaller than zero)

LCID

Load curve Id for loading (engineering stress vs. engineering strain)

F0

Initial Tensile Force

TMAXF0

Time for which pre-tension force will be held

TRAMP

Ramp-up time for pre-tension force

IREAD

Flag: If value greater than zero, use the value of OUTPUT from card 2.

OUTPUT

Flag = 1 to output axial strain

Remarks: 1. The force, F generated by the cable is nonzero if the cable is in tension. The force is given by: F = max (F0 + KΔL, 0.) where K is the stiffness, and ΔL is the change in length. If E is greater than zero, K is defined as: K = (E X cross sectional area)/ (Initial length - offset) 2. A constant force element can be obtained by setting: F0 > 0, and K = 0

18 Materials

3. The cross section, and offset are defined on the *SECTION or *ELEMENT cards. For a slack cable, the offset should be input as a negative value. For an initial tensile force, the offset should be positive. 4. If a load curve is specified, the Young’s modulus will be ignored, and the load curve will be used instead. The points on the load curve are defined as engineering stress vs. engineering strain. The unloading behavior follows the loading. See Also: • LS-DYNA Keyword User’s Manual MAT_ELASTIC This LS-DYNA material model (001) is an isotropic elastic material available for beam, shell and solid elements.

Field

Contents

Title

Unique name identifying the material model.

Desc

Optional description of the material model.

TITLE_OPTION

If selected, the material Title will be exported to LS-DYNA

MID

Material identification number. (Integer > 0)

RO

Mass density.

E

Young’s modulus

PR

Poisson’s ratio

DA

Axial damping factor (used in Belytscho-Schwer beam type 2 only)

DB

Bending damping factor (used in Belytscho-Schwer beam type 2 only)

Remarks: 1. The axial and bending damping factors are used to damp down numerical noise. The update of the force resultants, F i , and moment resultants, M i , includes the damping factors:

Materials 19 Materials

n+1

Fi

n+1

Mi

n DA n+1⁄2 = F i +  1 + -------- ΔF i Δt

DB n n+1⁄2 = M i +  1 + -------- ΔM i Δt

See Also: • LS-DYNA Keyword User’s Manual MAT_ELASTIC_FLUID This LS-DYNA material model (001) is an isotropic elastic material available for solid elements.

Field

Contents

Title

Unique name identifying the material model.

Desc

Optional description of the material model.

TITLE_OPTION

If selected, the material Title will be exported to LS-DYNA

MID

Material identification number. (Integer > 0)

RO

Mass density.

E

Young’s modulus

PR

Poisson’s ratio

DA

Axial damping factor (used in Belytscho-Schwer beam type 2 only)

DB

Bending damping factor (used in Belytscho-Schwer beam type 2 only)

K

Bulk Modulus (for fluid option)

VC

Tensor viscosity coefficient (between 0.1 and 0.5)

CP

Cavitation pressure (default = 1.0E+20)

20 Materials

Remarks: 1. The axial and bending damping factors are used to damp down numerical noise. The update of the force resultants, F i , and moment resultants, M i , includes the damping factors: n+1

n DA n+1⁄2 = F i +  1 + -------- ΔF i Δt

n+1

DB n n+1⁄2 = M i +  1 + -------- ΔM i Δt

Fi

Mi

2. Fluid like behavior is obtained with the following relationship between bulk modulus, K, and pressure rate, p:

E K = -----------------------3 ( 1 – 2υ ) ·· p = – Kε ii A tensor viscosity VC, if used, which acts only on the deviatoric stresses See Also: • LS-DYNA Keyword User’s Manual MAT_ELASTIC_PLASTIC_THERMAL Temperature dependent material coefficients can be defined using this material type. A minimum of two temperature points are needed, and a maximum of eight can be defined.

Field

Comments

Title

Unique name identifying material model

Desc

Optional description of the material model

TITLE_OPTION

If selected material title option is used

Materials 21 Materials

Field

Comments

MID

Material identification number (Integer > 0)

RO

Mass Density of the material

YM_LC

Load curve defining Young’s modulus Vs. Temperatures.

PR_LC

Load curve defining Poisson’s raito Vs. Temperatures.

A_LC

Load curve defining the coefficent of thermal expansion Vs. Temperatures.

SIGY_LC

Load curve defining Yield stressVs. Temperatures.

V_LC

Load curve defining the plastic hardening modulus Vs. Temperatures.

See Also: • LS-DYNA Keyword User’s Manual MAT_ISOTROPIC_ELASTIC_PLASTIC Defines an isotropic plasticity material with isotropic hardening. This is a very low cost plasticity model, suitable for 3D solids and plane stress elements. If used in shell elements, this material model leads to inaccurate shell thickness updates and stresses after yielding.

Field

Contents

Name

Unique name identifying the material model.

Desc

Optional description of the material model.

Fields: MID

Material identification number. (Integer > 0)

RO

Mass density.

G

Shear modulus.

SIGY

Yield Stress.

ETAN

Plastic hardening modulus

BULK

Bulk modulus

22 Materials

Remarks: 1. In the plane stress implementation for shell elements, a one-step radial return approach is used to scale the Cauchy stress tensor if the state of stress exceeds the yield surface. See Also: • LS-DYNA Keyword User’s Manual MAT_LOW_DENSITY_FOAM This material is used to model highly compressible low density foams. Its main applications are for seat cushions and padding on the Side Impact Dummies (SID). Optionally, a tension cut-off failure can be defined.

Field

Contents

Name

Unique name identifying the material model.

Desc

Optional description of the material model.

Fields: MID

Material identification number. (Integer > 0)

RO

Mass density.

E

Young’s modulus

LCID

Load Curve Id for nominal stress versus strain

TC

Tension cut-off stress

HU

Hysteric unloading factor (between 0 and 1). Default is 1 (no energy dissipation)

BETA

Decay constant (β) for creep in unloading

Materials 23 Materials

Field DAMP

Contents Viscous damping coefficient (0.05< recommended value < 0.50) to model damping effects. LT. 0: the absolute value of DAMP is used as the load curve which defines the damping coefficient as a function of the maximum strain in compression εmax (see Remark 1). In tension, the damping constant is set to the value corresponding to the strain at 0.

SHAPE

Shape factor for unloading. Active for non-zero values of the Hysteric unloading factor (HU)

FAIL

Failure option, after cut-off stress reached. = 0, Tensile stress remains at cut-off value = 1, Tensile stress is reset to zero

BVFLAG

Bulk viscosity activation flag = 0, No bulk viscosity (recommended, default) = 1, Bulk viscosity active

ED

Young’s relaxation modulus Ed (optional), for rate effects.

BETA1

Optional Decay constant β1

KCON

Stiffness coefficient for contact interface stiffness. If undefined, the maximum slope in the stress vs. strain curve is used.

REF

Use Reference geometry to initialize the stress tensor. The reference geometry is defined by the keyword: *INITIAL_FOAM_REFERENCE_GEOMETRY. = 0, Off = 1, On

Remarks: The compressive behavior is illustrated in Figure 1 where hysteresis on unloading is shown. This behavior under uniaxial loading is assumed not to significantly couple in the transverse directions. In tension the material behaves in a linear fashion until tearing occurs. Although the implementation may be somewhat unusual, it was motivated by Storakers (1986). The model uses tabulated input data for the loading curve where the nominal stresses are defined as a function of the elongations, εi , which are defined in terms of the principal stretches, λ i , as:

εi = λi – 1

24 Materials

The stretch ratios are found by solving for the eigenvalues of the left stretch tensor, V ij , which is obtained via a polar decomposition of the deformation gradient matrix, F ij . Recall that,

F ij = R ik Ukj = V ik Rkj The update of Vij follows the numerically stable approach of (Taylor and Flanagan 1989). After solving for the principal stretches, we compute the elongations and, if the elongations are compressive, the corresponding values of the nominal stresses, τi are interpolated. If the elongations are tensile, the nominal stresses are given by

τ i = Eε i and the Cauchy stresses in the principal system become

τi σ i = ---------λ i λk The stresses can now be transformed back into the global system for the nodal force calculations. Additional Remarks: 1. When hysteretic unloading is used the reloading will follow the unloading curve if the decay constant, β , is set to zero. If β is nonzero the decay to the original loading curve is governed by the expression:

1. – e

– βt

2. The bulk viscosity, which generates a rate dependent pressure, may cause an unexpected volumetric response and, consequently, it is optional with this model. 3. The hysteretic unloading factor results in the unloading curve to lie beneath the loading curve as shown below. This unloading provide energy dissipation which is reasonable in certain kinds of foam. 4. Note that since this material has no effective plastic strain, the internal energy per initial volume is written into the output databases. 5. Rate effects are accounted for through linear viscoelasticity by a convolution integral of the form r

σ ij =

∂ε kl --------- dτ g ( t – τ ) 0 ijkl ∂τ t

where g ijkl ( t – τ ) is the relaxation function. The stress tensor augments the stresses determined from the foam. Consequently, the final stress, σ ij is taken as the summation of the two contributions: f

r

σ ij = σ ij + σ ij

Materials 25 Materials

Since we wish to include only simple rate effects, the relaxation function is represented by one term from the Prony series: N

g ( t ) = α0 +



am e

– βt

m=1

given by,

g ( t ) = Ed e

–β1 t

This model is effectively a Maxwell fluid which consists of a damper and spring in series. We characterize this in the input by a Young's modulus, Ed , and decay constant, β 1 .The formulation is performed in the local system of principal stretches where only the principal values of stress are computed and triaxial coupling is avoided. Consequently, the one-dimensional nature of this foam material is unaffected by this addition of rate effects. The addition of rate effects necessitates twelve additional history variables per integration point. The cost and memory overhead of this model comes primarily from the need to “remember” the local system of principal stretches.

Figure 1

Behavior of the Low Density Urethane Foam Model

6. The time step size is based on the current density and the maximum of the instantaneous loading slope, E, and ECON. If ECON is undefined the maximum slope in the loading curve is used instead. See Also: • LS-DYNA Keyword User’s Manual

26 Materials

MAT_MOONEY_RIVLIN_RUBBER This LS-DYNA material is used to define material properties for a two-parameter material model for rubber.

Field

Contents

Name

Unique name identifying the material model.

Desc

Optional description of the material model.

Fields: MID

Material identification number. (Integer > 0)

PR

Poisson’s ratio.

RO

Mass density.

A

Mooney Rivlin Constant, A

B

Mooney Rivlin Constant, B

REF

Use Reference geometry to initialize the stress tensor =0, Off = 1, On

SGL

Specimen Gauge length, l0

SW

Specimen width

ST

Specimen thickness

LCID

Load Curve Id defining the force versus actual length change (ΔL) in the gauge length.

Remarks: The strain energy density function is defined as:

W = A ( I – 3 ) + B ( II – 3 ) + C ( III

–2

– 1 ) + D ( III – 1 )

2

Materials 27 Materials

C = 0.5A + B D = A(5ν - 2) + B(11ν -5)/(2(1 - 2ν)) ν = Poisson’s ratio 2(A + B) = Shear modulus of linear elasticity I, II, III are the three invariants of the Cauchy-Green Tensor The load curve definition that provides the uniaxial data should give the change in gauge length, Δ L , versus the corresponding force. In compression both the force and the change in gauge length must be specified as negative values. In tension the force and change in gauge length should be input as positive values. The principal stretch ratio in the uniaxial direction, λ 1 , is then given by

L 0 + ΔL λ 1 = -----------------L0 with L0 being the initial length and L being the actual length. Alternatively, the stress versus strain curve can also be input by setting the gauge length, thickness, and width to unity (1.0) and defining the engineering strain in place of the change in gauge length and the nominal (engineering) stress in place of the force (Figure 2).

28 Materials

Figure 2

Uniaxial Specimen for Experimental Data

The least square fit to the experimental data is performed during the initialization phase and is a comparison between the fit and the actual input is provided in the printed file. It is a good idea to visually check to make sure that it is acceptable. The coefficients A and B are also printed in the Dyna output file. The stress versus strain curve can used instead of the force versus the change in the gauge length by setting the gauge length, thickness, and width to unity (1.0) and defining the engineering strain in place of the change in gauge length and the nominal (engineering) stress in place of the force (Figure 3).

Figure 3

Experimental Data from Uniaxial Specimen

See Also: • LS-DYNA Keyword User’s Manual

Materials 29 Materials

MAT_NONLOCAL Defines failure criterion to be dependent on the state of the material within a radius of influence which surrounds the integration point. With this failure model, the mesh size sensitivity of failure is greatly reduced, giving better convergence to a unique solution as the mesh is refined.

Field

Comments

Title

Unique name identifying material model

Desc

Optional description of the material model

TITLE_OPTION

If selected material title option is used

MID

Non local Material identification number (Integer > 0)

PID

Part Id for non local material

P

Exponent of weighting function. A typical value might be 8., depending on the choice of the value for L.

Q

Exponent of weighting function. A typical value might be 2.

L

Characteristic length. This length should span a few elements

NFREQ

Number of time steps before updating neighbors. Since the nearest neighbor search can add significant computational time, NFREQ should be set to value of 10 to 100.

NL1,,, NL8

History variable Ids for non local treatment

XC1, YC1, ZC1

Coordinate of point on symmetry plane

XC2, YC2, ZC2

Coordinate of a point along the normal vector

See Also: • LS-DYNA Keyword User’s Manual

30 Materials

MAT_ORTHOTROPIC_ELASTIC This LS_Dyna material model (002) is an orthotropic elastic material available for solids, shells, and thick shells.

Field

Contents

Title

Unique name identifying the material model.

Desc

Optional description of the material model.

TITLE_OPTION

If selected, the material Title will be exported to LS-DYNA

MID

Material identification number. (Integer > 0)

RO

Mass density.

EA

Young’s modulus in a-direction

EB

Young’s modulus in b-direction

EC

Young’s modulus in c-direction

PRBA

Poisson’s ratio (νba)

PRCA

Poisson’s ratio (νca)

PRCB

Poisson’s ratio (νcb)

GAB

Shear modulus (Gab)

GBC

Shear modulus (Gbc)

GCA

Shear modulus (Gca)

AOPT

Material axis option

G

Shear modulus for frequency dependent damping

SIGF

Limit stress for frequency independent frictional damping

XP, YP, ZP

Coordinates for point P (for AOPT= 1 and 4)

Materials 31 Materials

Field

Contents

A1, A2, A3

Components of a vector a (for AOPT=2)

D1, D2, D3

Components of a vector d (for AOPT=2)

V1, V2, V3

Components of a vector v (for AOPT= 3 and 4)

BETA

Material angle in degrees (for AOPT= 3)

REF

Use Reference geometry to initialize the stress tensor

Remarks: The material law that relates stresses to strains is defined as: T

C = T CL T ˜ ˜ ˜ ˜ where T is a transformation matrix, and C L is the constitutive matrix defined in terms of the material ˜

˜

constants of the orthogonal material axes,

a , b , and c . The inverse of CL for the orthotropic case is ˜

defined as:

–1

CL ˜

1- ν ba ν ca ----– -------- – ------- 0 Ea Eb Ec

0

0

ν ab 1 ν cb – -------- ------ – ------- 0 Ea Eb Ec

0

0

0

0

1-------0 G ab

0

νac ν bc 1 – ------- – ------- ----Ea Eb Ec =

Note that

0

0

0

0

0

0

0

1 0 --------- 0 G bc

0

0

0

0

1 0 --------G ca

ν ab ν ba ν ca ν ac ν cb ν bc -------- = -------, ------- = ------, ------- = ------Ea Eb Ec E a Ec Eb

32 Materials

The frequency independent damping is obtained by having a spring and slider in series as shown in the following sketch:

G

σ fric This option applies only to orthotropic solid elements and affects only the deviatoric stresses. See Also: • LS-DYNA Keyword User’s Manual MAT_PIECEWISE_LINEAR_PLASTICITY Defines elasto-plastic material with an arbitrary stress versus strain curve and arbitrary strain rate dependency. Also, failure based on a plastic strain or a minimum time step size can be defined.

Field

Contents

Name

Unique name identifying the material model.

Desc

Optional description of the material model.

Fields: MID

Material identification number. (Integer > 0)

E

Young’s modulus. (Real > 0.0 or blank)

PR

Poisson’s ratio.

RO

Mass density.

SIGY

Yield Stress.

ETAN

Tangent modulus (ignored if LCSS.GT. 0 is defined)

Materials 33 Materials

Field

Contents

FAIL

Failure Flag LT. 0: User defined failure subroutine is called to determine failure EQ. 0.0: Failure not considered GT. 0.0: Plastic strain to failure. When the plastic strain reaches this value, the element is deleted from the calculation.

TDEL

Minimum time step size for automatic element deletion

C

Strain rate parameter, C

P

Strain rate parameter, P

LCSS

Load Curve Id or Table Id defining effective stress versus effective plastic strain. The tableId defined for each strain rate a value of load curve Id giving the stress versus effective plastic strain for that rate.

LCSR

Load Curve Id defining strain rate scaling effect on yield stress

VP

Formulation for rate effects =-1, Cowper-Symnods with deviatoric strain rate rather than total = 0, Scale yield stress = 1, Viscoplastic formulation

Remarks: The stress strain behavior may be treated by a bilinear stress strain curve by defining the tangent modulus, ETAN. The most general approach is to use the table definition (LCSS) discussed below. Three options to account for strain rate effects are possible. 1. Strain rate may be accounted for using the Cowper and Symonds model which scales the yield stress with the factor

· ε 1⁄p 1 +  ---- C where, ε· is the strain rate

· ε =

· · ε ij ε ij

If VP=-1, the deviatoric strain rates are used instead. If the viscoplastic option is active, VP=1.0, and if SIGY is > 0 then the dynamic yield stress is computed from the sum of the static stress,

34 Materials

s

p

σ y ( ε eff ) which is typically given by a load curve ID, and the initial yield stress, SIGY, multiplied by the Cowper-Symonds rate term as follows: p ·p σ y ( ε eff, ε eff )

 ε· eff + SIGY ⋅  -------  C p

=

s p σ y ( ε eff )

1⁄p

where the plastic strain rate is used. If SIGY=0, the following equation is used instead where the static stress s

p

σ y ( ε eff ) must be defined by a load curve: p ·p σ y ( ε eff, ε eff )

 ε· eff 1 +  -------  C p

=

s p σ y ( ε eff )

1⁄p

This latter equation is always used if the viscoplastic option is off. 2. For complete generality a load curve (LCSR) to scale the yield stress may be input instead. In this curve the scale factor versus strain rate is defined. 3. If different stress versus strain curves can be provided for various strain rates, the option using the reference to a table (LCSS) can be used. See figure below.

Materials 35 Materials

Figure 4

Rate effects may be accounted for by defining a table of curves. If a table Id is specified a curve Id is given for each strain rate. Intermediate values are found by interpolating between curves. Effective plastic strain versus yield stress is expected. If the strain rate values fall out of range, extrapolation is not used; rather, either the first or last curve determines the yield stress depending on whether the rate is low or high, respectively.

4. A fully viscoplastic formulation is optional (variable VP) which incorporates the different options above within the yield surface. An additional cost is incurred over the simple scaling but the improvement in results can be dramatic. See Also: • LS-DYNA Keyword User’s Manual

36 Materials

MAT_PLASTIC_KINEMATIC Defines elasto-plastic material with isotropic and kinematic hardening with or without rate effects.

Field

Contents

Name

Unique name identifying the material model.

Desc

Optional description of the material model.

Fields: MID

Material identification number. (Integer > 0)

E

Young’s modulus. (Real > 0.0 or blank)

PR

Poisson’s ratio.

RO

Mass density.

SIGY

Yield Stress.

ETAN

Tangent modulus

BETA

Hardening parameter = 0: Kinematic hardening = 1: Isotropic hardening 1 < BETA > 0: Combined hardening

SRC

Strain rate parameter, C, for Cowper Symonds strain rate model. If zero, rate effects are ignored.

SRP

Strain rate parameter, P, for Cowper Symonds strain rate model. If zero, rate effects are ignored.

FS

Failure strain for eroding elements

VP

Formulation for rate effects: = 0, Scale yield stress (default) = 1, Viscoplastic formulation

Materials 37 Materials

Remarks:

Figure 5

Elastic-plastic behavior with kinematic and isotropic hardening where l0 and l are respectively undeformed and deformed lengths of uniaxial tension specimen, and Et is the slope of the bilinear stress vs. strain curve.

Strain rate may be accounted for using the Cowper and Symonds model which scales the yield stress with the factor

· ε 1⁄p 1 +  ---- C where, ε· is the strain rate

38 Materials

· ε =

· · ε ij ε ij

A fully viscoplastic formulation is optional which incorporates the Cowper and Symonds formulation within the yield surface. Although an additional computational cost is incurred, the improvement in the results can be substantial. To ignore strain rate effects, set both SRC and SRP to zero. See Also: • LS-DYNA Keyword User’s Manual MAT_POWER_LAW_PLASTICITY Defines an isotropic plasticity material model with rate effects which uses a power law for hardening.

Field

Contents

Name

Unique name identifying the material model.

Desc

Optional description of the material model.

Fields: MID

Material identification number. (Integer > 0)

RO

Mass density.

E

Young’s modulus. (Real > 0.0 or blank)

PR

Poisson’s ratio.

K

Strength coefficient

N

Hardening exponent

SRC

Strain rate parameter, C. If zero, rate effects are ignored.

SRP

Strain rate parameter, P. If zero, rate effects are ignored.

Materials 39 Materials

Field

Contents

SIGY

Yield Stress (optional). Generally this parameter is not necessary (See Remarks)

VP

Formulation for rate effects: = 0, Scale yield stress (default) = 1, Viscoplastic formulation

Remarks: The yield stress, σy is a function of plastic strain, and obeys the following equation:

σ y = k ε n = k ( ε yp + ε p )

n

where, ε· yp is the strain rate to yield, and ε p is the effective plastic strain (logarithmic). The parameter SIGY governs how the strain to yield is identified. If SIGY is set to zero, the strain to yield is found by solving for the intersection of the linear elastic loading with the strain hardening equation:

σ = Eε σ =kεn which gives the elastic strain at yield as:  1 

ε yp

E  n −1  =   k

If SIGY is set to nonzero, and greater than 0.02 then: 1 

ε yp

 σ   n  = y   k 

40 Materials

Strain rate is accounted for using the Cowper-Symonds model which scales the yield stress with the following factor:

 ε  1+  C 

1

P

where ε· is the strain rate. A fully viscoplastic formulation is optional with this model which incorporates the Cowper-Symonds formulation within the yield surface. Although an additional cost

is incurred, the improvement in results can be substantial. See Also: • LS-DYNA Keyword User’s Manual MAT_RIGID This material model is used to model parts made from rigid materials. Also, the coupling of a rigid body with MADYMO, and CAL3D can be defined via this material. Alternatively, a VDA surface can be attached as surface to model the geometry, e.g., for the tooling in metal-forming applications. Also, global and local constraints on the mass center can be optionally defined. Optionally, a local consideration for output and user-defined airbag sensors can be chosen.

Field

Contents

Title

Unique name identifying the material model.

Desc

Optional description of the material model.

TITLE_OPTION

If selected, the material Title will be exported to LS-DYNA

MID

Material identification number. (Integer > 0)

Materials 41 Materials

Field

Contents

RO

Mass density

E

Young’s modulus. (Real > 0.0 or blank)

PR

Poisson’s ratio

N

MADYMO3D coupling flag.

COUPLE

Coupling Option

ALIAS

VDA Surface alias Name

CMO

Center of mass constraint option =1, Constraints applied in global directions =0, No constraints =-1, Constraints applied in local directions

CON1

First constraint parameter =0, No constraints =1, Constrained x displacement =2, Constrained y displacement =3, Constrained z displacement =4, Constrained x and y displacements =5, Constrained y and z displacements =6, Constrained z and x displacements =7, Constrained x, y, and z displacements

42 Materials

Field CON2

Contents Second constraint parameter =0, No constraints =1, Constrained x rotation =2, Constrained y rotation =3, Constrained z rotation =4, Constrained x and y rotations =5, Constrained y and z rotations =6, Constrained z and x rotations =7, Constrained x, y, and z rotations

LCO

Local coordinate system for output

A1-V3

The components of two vectors a and v fixed in the rigid body for output.

Remarks: 1. A rigid material provides a convenient way of turning one or more parts comprised of beams, shells, or solid elements into a rigid body. Approximating a deformable body as rigid is a preferred modeling technique in many real world applications. For example, an engine block in a car crash simulation can be treated as rigid. Elements belonging to a rigid material are bypassed in the element processing and no storage is allocated for storing history variables. Consequently, using a rigid material is very cost efficient. 2. The inertial properties are calculated from the geometry of the constituent elements and the density RO as specified on the MAT_RIGID. 3. The initial velocity of a rigid material is calculated from the initial velocity of the constituent grids. 4. A rigid body can be made up of disjoint meshes. All elements that are part of a rigid body will move together as one rigid, even if they are disjoint. 5. Motion control for a rigid material can be defined using the BOUNDARY_SPC entry. The SPC must be applied to one grid point only. 6. Load control for a rigid material can be defined using the FORCE and MOMENT entries. These loads can be applied to any grid point that belongs to the rigid body. The forces and moments acting on the grid points will be accumulated and applied to the rigid body. 7. If no constraints are specified for the rigid material (CMO=0) the nodes belonging to the rigid material are scanned to determine constraints of the rigid material in global directions. If constraints are specified for the rigid material (CMO equal to +1 or –1), the nodes belonging to the rigid material are not scanned

Materials 43 Materials

8. Constraint directions for rigid materials (CMO equal to +1 or –1) are fixed, that is, not updated, with time. See Also: • LS-DYNA Keyword User’s Manual MAT_SEATBELT This material model is used to define the stretch characteristics and mass properties for seat belts.

Field

Comments

Title

Unique name identifying material model

Desc

Optional description of the material model

TITLE_OPTION

If selected material title option is used

MID

Material identification number (Integer > 0)

MPUL

Mass per unit length

LLCID

Load curve Id for loading (Force vs. engineering strain)

ULCID

Load curve Id for unloading (Force vs. engineering strain)

LMIN

Minimum length for elements connected to slip rings and retractors

Remarks: 1. The Load curves for loading and unloading should start at the origin (0, 0), and contain positive force and strain values only. The belt material is tension only, with zero forces being calculated whenever the strain becomes negative (compressive). The first nonzero point on the loading curve defines the initial yield point of the material. On unloading, the unloading curve is shifted along the strain axis until it crosses the loading curve at the yield point from which unloading starts. If the initial yield has not yet exceeded, or the origin of the (shifted) unloading curve is at negative strain, the original loading curve will be used for both loading and unloading. If the strain is less than the strain at the origin of the unloading curve, the belt is slack, and no force is generated. Otherwise, forces will be determined by the unloading curve for unloading, and reloading until the strain again exceeds yield after which the loading curve will again be used.

44 Materials

2. A small amount of damping is automatically included, to reduce high frequency oscillation. The damping force, D opposes the relative motion of the nodes, and is limited by stability: D = (0.1 X Mass X Relative velocity)/(Time step size) The magnitude of the damping force is limited to one-tenth of the force calculated from the force vs. strain relationship, and is zero when the belt is slack. Damping forces are not applied to elements attached to slip rings and retractors. See Also: • LS-DYNA Keyword User’s Manual MAT_SOIL_AND_FOAM This simple material model works similar to fluid. It should be used only in situations when soils and foams are confined within a structure or when geometric boundaries are present.

Field

Comments

Title

Unique name identifying material model

Desc

Optional description of the material model

TITLE_OPTION

If selected material title option is used

MID

Material identification number (Integer > 0)

RO

Mass Density of the material

G

Shear modulus

BULK

Bulk modulus for unloading

A0, A1, A2

Yield function constants

PC

Pressure cut off for tensile fracture

VCR

Volumetric crushing option: 0.0: on, 1.0: loading and unloading paths are the same

Materials 45 Materials

Field

Comments

REF

use reference geometry to initialize the pressure

LCID

Load curve Id defining pressure vs. volumetric strain

Remarks: 1. Pressure is positive in compression 2. Volumetric strain is given by the natural log of the relative volume and is negative in compression 3. Relative volume is the ratio of current volume to the initial volume at the start of the calculation 4. If the pressure drops below the cutoff value specified, it is reset to that value See Also: • LS-DYNA Keyword User’s Manual MAT_VISCOELASTIC This material model is used to define viscoelastic behavior for beams (Hughes-Liu), shells, and solids

Field

Comments

Title

Unique name identifying material model

Desc

Optional description of the material model

TITLE_OPTION

If selected material title option is used

MID

Material identification number (Integer > 0)

RO

Mass Density of the material

BULK

Bulk modulus for unloading

G0

Short time shear modulus

GI

long time (Infinite) Shear modulus

BETA

Decay constant

Remarks: 1. The shear relaxation behavior is described by [Hermann and Peterson, 1968]:

G ( t ) = GI + ( G0 – GI )e

– βt

46 Materials

See Also: • LS-DYNA Keyword User’s Manual MAT_HIGH_EXPLOSIVE_BURN This material model is used to input the detonation properties of high explosive materials.

Field

Comments

Title

Unique name identifying material model

Desc

Optional description of the material model

TITLE_OPTION

If selected material title option is used

MID

Material identification number (Integer > 0)

RO

Mass Density of the material

D

Detonation Velocity

PCJ

Chapman-Jouget pressure

BETA

Beta burn flag 0: Beta and programmed burn 1: Beta burn only 2: Programmed burn only

K

Bulk Modulus (Beta = 2)

G

Shear Modulus (Beta = 2)

SIGY

Yield Stress (Beta = 2)

See Also: • LS-DYNA Keyword User’s Manual

Materials 47 Materials

MAT_NULL The use of this material model allows equations of state without computing deviatoric stresses.

Field

Comments

Title

Unique name identifying material model

Desc

Optional description of the material model

TITLE_OPTION

If selected material title option is used

MID

Material identification number (Integer > 0)

RO

Mass Density of the material

PC

Pressure Cutoff

MU

Dynamic Viscosity Coefficient

TEROD

Relative Volume for Erosion in Tension

CEROD

Relative Volume for Erosion in Compression

YM

Young’s Modulus (used for null beams and shells only)

PR

Poisson’s ratio (used for nul beams and shells only)

See Also: • LS-DYNA Keyword User’s Manual

48 Materials

MAT_ELASTIC_PLASTIC_HYDRO This material model is used to model an elastic-plastic hydrodynamic material.

Field

Comments

Title

Unique name identifying material model

Desc

Optional description of the material model

TITLE_OPTION

If selected material title option is used

MID

Material identification number (Integer > 0)

RO

Mass Density of the material

G

Shear Modulus

SIGY

Yield Stress

EH

Plastic hardening modulus

PC

Pressure Cutoff

FS

Failure strain for Erosion

LCID

Load curve Id defining pressure vs. volumetric strain

See Also: • LS-DYNA Keyword User’s Manual

Materials 49 Materials

MAT_ELASTIC_PLASTIC_HYDRO_SPALL This material model is used to model an elastic-plastic hydrodynamic material with spall to represent splitting, cracking, and failure under tensile loads.

Field

Comments

Title

Unique name identifying material model

Desc

Optional description of the material model

TITLE_OPTION

If selected material title option is used

MID

Material identification number (Integer > 0)

RO

Mass Density of the material

G

Shear Modulus

SIGY

Yield Stress

EH

Plastic hardening modulus

PC

Pressure Cutoff

FS

Failure strain for Erosion

A1

Linear Pressure Hardening Coefficient

A2

Quadratic Pressure Hardening Coefficient

SPALL

Spall Type

LCID

Load curve Id defining pressure vs. volumetric strain

See Also: • LS-DYNA Keyword User’s Manual

50 Materials

MAT_STEINBERG This material model is used to model materials deforming at very high strain rate for use with solid elements. The yield strength is a function of temperature and pressure.

Field

Comments

Title

Unique name identifying material model

Desc

Optional description of the material model

TITLE_OPTION

If selected material title option is used

MID

Material identification number (Integer > 0)

RO

Mass Density of the material

G0

Basic shear modulus

SIG0

Yield Stress, σ0

BETA

Parameter β, used in the equation defining Yield Strength

N

Parameter n, used in the equation defininig Yield Strength

GAMA

Initial Plastic Strain γi

SIGM

σm

B

Parameter b, used in the equation defininig Yield Strength

BP

Parameter b' , used in the equation defininig Yield Strength

H

Parameter h, used in the equation defininig Yield Strength

F

Parameter b, used in the equation defininig Yield Strength

A

Atomic Weight

TM0

Melting Temperature

Materials 51 Materials

Field

Comments

GAM0

Yield Stress equation Parameter, Gama_0

SA

Melting Temperature equation Parameter, a

PC

Pressure Cutoff

SPALL

Spall Type 0: Default set to 2.0 1: P >= PC 2: if σmax >= -PC, element spalls and tension, p < 0, is never allowed 3: P< -PC, element spalls and tension, p < 0, is never allowed

RP

Melting Temperature equation parameter, r'

FLAG

Set 1 for μ coefficients for the cold compression energy fit

NMN

Optional minimum value for μ or η

NMX

Optional maximum value for μ or η

ECi

Cold Compression Energy coefficients

See Also: • LS-DYNA Keyword User’s Manual

52 Materials

MAT_STEINBERG_LUND This material model is used to input the properties of a Steinberg and Lund [1999].material model for including the strain rate effect.

Field

Comments

Title

Unique name identifying material model

Desc

Optional description of the material model

TITLE_OPTION

If selected material title option is used

MID

Material identification number (Integer > 0)

RO

Mass Density of the material

G0

Basic shear modulus

SIG0

Yield Stress, σ0

BETA

Parameter β, used in the equation defininig Yield Strength

N

Parameter n, used in the equation defininig Yield Strength

GAMA

Initial Plastic Strain γi

SIGM

σm

B

Parameter b, used in the equation defininig Yield Strength

BP

Parameter b' , used in the equation defininig Yield Strength

H

Parameter h, used in the equation defininig Yield Strength

F

Parameter b, used in the equation defininig Yield Strength

Materials 53 Materials

Field

Comments

A

Atomic Weight

TM0

Melting Temperature

GAM0

Yield Stress equation Parameter, Gama_0

SA

Melting Temperature equation Parameter, a

PC

Pressure Cutoff

SPALL

Spall Type 0: Default set to 2.0 1: P >= PC 2: if σmax >= -PC, element spalls and tension, p < 0, is never allowed 3: P< -PC, element spalls and tension, p < 0, is never allowed

RP

Melting Temperature equation parameter, r'

FLAG

Set 1 for μ coeeficients for the cold compression energy fit

NMN

Optional minimum value for μ or η

NMX

Optional maximum value for μ or η

ECi

Cold Compression Energy coefficients

UK

Activation Energy for rate dependent model

C1

Exponent prefactor in rate dependent model

C2

Coefficient of drag term rate dependent model

YP

Peierls stress for rate dependent model

YA

Ahtermal yield stress for rate dependent model

YM

Work hardening max for rate dependent model

See Also: • LS-DYNA Keyword User’s Manual

54 Materials

MAT_ISOTROPIC_ELASTIC_FAILURE This material model is used to define the properties of a non-iterative plasticity model with simple plastic strain failure criteria.

Field

Comments

Title

Unique name identifying material model

Desc

Optional description of the material model

TITLE_OPTION

If selected material title option is used

MID

Material identification number (Integer > 0)

RO

Mass Density of the material

G

Shear Modulus

SIGY

Yield Stress

ETAN

Plastic Hardening Modulus

BULK

Bulk Modulus

EPF

Plastic Failure Strain

PRF

Failure Pressure

REM

Element Erosion option 0: Eroded at failure 1: no removal of element, (except if TERM = 1, and element time step size falls below Δt)

TREM

Δt for element removal 0: Δt is not considered 1: yes, if element time step size falls below Δt

Materials 55 Materials

See Also: • LS-DYNA Keyword User’s Manual MAT_SOIL_AND_FOAM_FAILURE This material model is used to define the material properties for a soil and foam model. This material model works similar to fluid, and should be used only in situations when soils and foams are confined within a structure or when geometric boundaries are present.In this material model, the material loses its ability to carry tension when the pressure exceeds the failure pressure.

Field

Comments

Title

Unique name identifying material model

Desc

Optional description of the material model

TITLE_OPTION

If selected material title option is used

MID

Material identification number (Integer > 0)

RO

Mass Density of the material

G

Shear Modulus

BULK

Bulk Modulus for unloading

A0, A1, A2

Plastic Yield Function Constants

PC

Pressure Cutoff for Tensile Fracture

VCR

Volumetric Crushing Option 0: On 1: Loading and unloading paths are the same

56 Materials

Field REF

Comments Use reference geometry to initialize pressure 0: Off 1:On

LCID

Load Curve Id defining pressure vs. volumetric strain

See Also: • LS-DYNA Keyword User’s Manual MAT_JOHNSON_COOK The Johnson-Cook material model is a strain and temperature sensitive plasticity model. It is sometimes used for materials with a large variation in the strain rate, and/or undergoing softening due to plastic heating.

Field

Comments

Title

Unique name identifying material model

Desc

Optional description of the material model

TITLE_OPTION

If selected material title option is used

MID

Material identification number (Integer > 0)

RO

Mass Density of the material

G

Shear Modulus

Materials 57 Materials

Field

Comments

E

Young’s Modulus (for shell elements only)

PR

Poisson’s Ratio (for shell elements only)

DTF

Minimum Time step for Automatic Shell Element Deletion

VP

Formulation for Rate Effects 0: Scale Yield Stress 1: ViscoPlastic Formulation

RATEOP

Optional forms of strain-rate term: .EQ. 0: Log-Linear Johnson-Cook (default) .EQ. 1: Log-Quadratic Huh-Kang (2 parameters) .EQ. 2: Exponential Allen-Rule_jones .EQ. 3: Exponential Cowper-Symonds (2 parameters)

A, B, N, C, M

Constants to define the flow stress equation

TM

Melt Temperature

TR

Room Temperature

EPSO

Effective Plastic Strain Rate depends on Time Unit

CP

Specific Heat

PC

Pressure Cutoff (Pmin< 0.0)

SPALL

Spall Type 0: Default set to 2.0 1: P >= PC 2: if σmax >= -PC, element spalls and tension, p < 0, is never allowed 3: P< -PC, element spalls and tension, p < 0, is never allowed

IT

Plastic Strain Iteration 0: No Iteration 1: Accurative Iteration Solution

Di

Failure Parameters

C2/P

Optional strain-rate parameter for Huh-Kang (C2), or Cowper-Symonds (P) forms.

58 Materials

See Also: • LS-DYNA Keyword User’s Manual MAT_PSEUDO_TENSOR This material model is used to define the properties a pseudo-tensor material model. This has been used to analyze buried steel reinforced concrete structures subjected to impulsive loadings.

Field

Comments

Title

Unique name identifying material model

Desc

Optional description of the material model

TITLE_OPTION

If selected material title option is used

MID

Material identification number (Integer > 0)

RO

Mass Density of the material

G

Shear Modulus

PR

Poisson’s Ratio

SIGF

Tension Cutoff (Maximum Principal Stress at failure)

A0

Cohesion

A1, A2

Pressure Hardening Coefficients

A0F

Cohesion for failed material

A1F

Pressure hardening coefficient for failed material

B1

Damage Scaling Factor

PER

Percent Reinforcement

Materials 59 Materials

Field

Comments

ER

Young’s Modulus for Reinforcement

PRR

Poisson’s Ratio for Reinforcement

SIGY

Initial Yield Stress

ETAN

Tangent Modulus/Plastic Hardening Modulus

LCP

Load Curve Id defining rate sensitivity for principal material

LCR

Load Curve Id defining rate sensitivity for reinforcement

LCID

Load Curve defining Yield Stress (or scale factor) vs. effective plastic strains, damages, or pressures

See Also: • LS-DYNA Keyword User’s Manual MAT_ORIENTED_CRACK Defines the properties of brittle materials failing due to large tensile stresses.

Field

Comments

Title

Unique name identifying material model

Desc

Optional description of the material model

TITLE_OPTION

If selected material title option is used

MID

Material identification number (Integer > 0)

RO

Mass Density of the material

E

Young’s Modulus

PR

Poisson’s Ratio

SIGY

Yield Stress

ETAN

Plastic Hardening Modulus

FS

Fracture Stress

PRF

Fracture Pressure

60 Materials

See Also: • LS-DYNA Keyword User’s Manual MAT_STRAIN_RATE_DEPENDENT_PLASTICITY Defines the properties of a strain rate dependent material.

Field

Comments

Title

Unique name identifying material model

Desc

Optional description of the material model

TITLE_OPTION

If selected material title option is used

MID

Material identification number (Integer > 0)

RO

Mass Density of the material

E

Young’s Modulus

PR

Poisson’s Ratio

VP

Formulation for Rate Effects 0: Scale Yield Stress 1: Viscoplastic Formulation

LC1

Load Curve Id for Yield Stress σ0 vs. effective strain rate

ETAN

Tangent Modulus

LC2

Load Curve Id for Young’s Modulus vs. effective strain rate

LC3

Load Curve Id for Tangent Modulus vs. effective strain rate

LC4

Load Curve Id for von Mises stress at failure vs. effective strain rate

TDEL

Time Step Size for Automatic Element Deletion (shell elements only)

RDEF

Redefinition of failure curve 1: Effective plastic strain 2: Maximum principal stress

Materials 61 Materials

See Also: • LS-DYNA Keyword User’s Manual MAT_ORTHOTROPIC_THERMAL Defines the properties of a linear elastic material with temperature dependent orthotropic properties.

Field

Comments

Title

Unique name identifying material model

Desc

Optional description of the material model

TITLE_OPTION

If selected material title option is used

MID

Material identification number (Integer > 0)

RO

Mass Density of the material

EA, EB, EC

Young’s Moduli in the A, B and C direction

PRBA, PRCA, PRCB

Poisson’s Ratio in the ba, ca and cb directions

GAB, GBC, GCA

Shear Moduli in the ab, bc and ca directions

AA, AB, AC

Coefficients of Thermal Expansion in the a, b, and c directions

62 Materials

Field AOPT

Comments Material Axes option 0: Locally orthotropic with material axes determined by element nodes 1, 2, and 4. (Node 1 is the local origin, Node 2 is along the local a- axis; Local c-axis is the cross product of local a-axis, and the vector from node 1 to node 4; Local b- axis is the cross product of local c- and a- axes.) 1: Locally orthotropic with material axis determined by a point in space, and the global location of the element center; this is the a- direction. This option is for solid elements only. 2: Globally orthotropic with material axis determined by3 vectors below. 3: Locally orthotropic with material axis determined by rotating the material axes about the element normal by an angle, BETA, from a line in the plane of the element defined by the cross product of the vector v with the element normal. 4: Locally orthotropic in cylindrical coordinate system with the material axis determined by a vector v, and an originating point, P, which defines the center line axis. This option is for solid elements only.

XP

X-coordinate of point p for AOPT=1

YP

Y-coordinate of point p for AOPT=1

ZP

Z-coordinate of point p for AOPT=1

Ai

Component of Vector a, for AOPT=2

Vi

Component of Vector v, for AOPT=3

Di

Component of Vector d, for AOPT=2

BETA

Material Angle (Degrees), for AOPT = 3

REF

Use Reference Geometry to initialize stress tensor (0 = off; 1 = on)

See Also: • LS-DYNA Keyword User’s Manual

Materials 63 Materials

MAT_COMPOSITE_DAMAGE Defines the properties of an orthrotropic material with optional brittle failure for composites.

Field

Comments

Title

Unique name identifying material model

Desc

Optional description of the material model

TITLE_OPTION

If selected material title option is used

MID

Material identification number (Integer > 0)

RO

Mass Density of the material

EA, EB, EC

Young’s Moduli in the A, B and C direction

PRBA, PRCA, PRCB

Poisson’s Ratio in the ba, ca and cb directions

GAB, GBC, GCA

Shear Moduli in the ab, bc and ca directions

KF

Bulk Modulus of failed material

64 Materials

Field AOPT

Comments Material Axes option 0: Locally orthotropic with material axes determined by element nodes 1, 2, and 4. (Node 1 is the local origin, Node 2 is along the local a- axis; Local c-axis is the cross product of local a-axis, and the vector from node 1 to node 4; Local b- axis is the cross product of loca c- and a- axes.) 1: Locally orthotropic with material axis determined by a point in space, and the global location of the element center; this is the a- direction. This option is for solid elements only. 2: Globally orthotropic with material axis determined by3 vectors below. 3: Locally orthotropic with material axis determined by rotating the material axes about the element normal by an angle, BETA, from a line in the plane of the element defined by the cross product of the vector v with the element normal. 4: Locally orthotropic in cylindrical coordinate system with the material axis determined by a vector v, and an originating point, P, which defines the centerline axis. This option is for solid elements only.

XP

X-coordinate of point p for AOPT=1

YP

Y-coordinate of point p for AOPT=1

ZP

Z-coordinate of point p for AOPT=1

Ai

Component of Vector a, for AOPT=2

Vi

Component of Vector v, for AOPT=3

Di

Component of Vector d, for AOPT=2

BETA

Material Angle

SC

Shear Strength, ab plane

XT

Longitudinal Tensile Strength, a-axis

YT

Transverse Tensile Strength, b-axis

YC

Transverse Compression Strength, b-axis

ALPH

Shear Stress Parameter for nonlinear term (0- 0.5)

SN

Normal Tensile Strength (solid elements only)

SYX

Transverse Shear Strength (solid elements only)

SZX

Transverse Shear Strength (solid elements only)

See Also: • LS-DYNA Keyword User’s Manual

Materials 65 Materials

MAT_TEMPERATURE_DEPENDENT_ORTHOTROPIC Defines the properties of an orthotropic elastic material with arbitrary temperature dependency.

Field

Comments

Title

Unique name identifying material model

Desc

Optional description of the material model

TITLE_OPTION

If selected material title option is used

MID

Material identification number (Integer > 0)

RO

Mass Density of the material

66 Materials

Field AOPT

Comments Material Axes option 0: Locally orthotropic with material axes determined by element nodes 1, 2, and 4. (Node 1 is the local origin, Node 2 is along the local a- axis; Local c-axis is the cross product of local a-axis, and the vector from node 1 to node 4; Local b- axis is the cross product of loca c- and a- axes.) 1: Locally orthotropic with material axis determined by a point in space, and the global location of the element center; this is the a- direction. This option is for solid elements only. 2: Globally orthotropic with material axis determined by3 vectors below. 3: Locally orthotropic with material axis determined by rotating the material axes about the element normal by an angle, BETA, from a line in the plane of the element defined by the cross product of the vector v with the element normal. 4: Locally orthotropic in cylindrical coordinate system with the material axis determined by a vector v, and an originating point, P, which defines the centerline axis. This option is for solid elements only.

REF

Use Reference Geometry to initialize stress tensor (0 = off; 1 = on)

MACF

Material axes change flag for brick element: =1 No Change; = 2 switch mateial axes a and b =3 switch material axes a and c ; =4 switch material axes b and c

XP

X-coordinate of point p for AOPT=1

YP

Y-coordinate of point p for AOPT=1

ZP

Z-coordinate of point p for AOPT=1

Ai

Component of Vector a, for AOPT=2

Vi

Component of Vector v, for AOPT=3

Di

Component of Vector d, for AOPT=2

BETA

Material Angle

EA_LC, EB_LC, EC_LC

Load curve defining Young’s Moduli in the a, b and c directions, respecively, vs. Temperature

PRBA_LC

Load curve defining Poisson’s Ratios in the ba directionsvs. Temperature

PRCA_LC

Load curve defining Poisson’s Ratios in the ca directionsvs. Temperature

PRCB_LC

Load curve defining Poisson’s Ratios in the cb directionsvs. Temperature

Materials 67 Materials

Field

Comments

AA_LC, AB_LC, AC_LC

Load curves defining Coefficients of Thermal Expansion in the a, b, and c directions, respectively, vs. Temperature

GAB_LC

Load curve defining Shear modulus in the ab plane vs. Temperature

GBC_LC

Load curve defining Shear modulus in the bc plane vs. Temperature

GCA_LC

Load curve defining Shear modulus in the ca plane vs. Temperature

See Also: • LS-DYNA Keyword User’s Manual MAT_GEOLOGIC_CAP_MODEL Defines the properties for geomechanical problems or materials like concrete.

Field

Comments

Title

Unique name identifying material model

Desc

Optional description of the material model

TITLE_OPTION

If selected material title option is used

MID

Material identification number (Integer > 0)

RO

Mass Density of the material

BULK

Initial Bulk Modulus

G

Initial Shear Modulus

ALPHA

Failure Envelope Parameter

THETA

Failure Envelope Linear coefficient

GAMMA

Failure Envelope Exponential coefficient

BETA

Failure Envelope Exponent

R

Cap, surface axis ratio

68 Materials

Field

Comments

D

Hardening law exponent

W

Hardening law coefficient

X0

Hardening Law Exponent

C

Kinematic Hardening Coefficient

N

Kinematic Hardening Parameter

PLOT

Plotting Flag for LS-Taurus

FTYPE

Formulation Flag 1: Soil or concrete 2: Rock

VEC

Vectorization Flag 0: Vectorized with a fixed number of iterations 1: Fully Iterative

TOFF

Tension Cutoff

See Also: • LS-DYNA Keyword User’s Manual

Materials 69 Materials

MAT_HONEYCOMB Defines the properties for honeycomb and foam materials with real anisotropic behavior.

Field

Comments

Title

Unique name identifying material model

Desc

Optional description of the material model

TITLE_OPTION

If selected material title option is used

MID

Material identification number (Integer > 0)

RO

Mass Density of the material

E

Young’s Modulus

PR

Poisson’s Ratio

SIGY

Yield Stress for fully compacted Honeycomb

VF

Relative Volume at which Honeycomb is fully compacted

MU

Material Viscosity Coefficient

BULK

Bulk Viscosity Flag 0: Bulk Viscosity Not Used 1: Bulk Viscosity Active and MU=0

LCA

Load Curve Id for (Sigma_aa vs. either Relative Volume or Volumetric Strain

LCB

Load Curve Id for (Sigma_bb vs. either Relative Volume or Volumetric Strain (Default LCB = LCA)

70 Materials

Field

Comments

LCC

Load Curve Id for (Sigma_cc vs. either Relative Volume or Volumetric Strain (Default LCC = LCA)

LCS

Load Curve Id for (shear stress vs. either Relative Volume or Volumetric Strain (Default LCS = LCA)

LCAB

Load Curve Id for (Sigma_ab vs. either Relative Volume or Volumetric Strain (Default LCAB = LCS)

LCBC

Load Curve Id for (Sigma_bc vs. either Relative Volume or Volumetric Strain (Default LCBC = LCS)

LCCA

Load Curve Id for (Sigma_ca vs. either Relative Volume or Volumetric Strain (Default LCCA = LCS)

LCSR

Load Curve Id for strain rate effects defining the scale factor vs. strain rate. The curves defined above are scaled using this curve.

EAAU, EBBU, ECCU

Elastic Moduli in uncompressed configuration in aa, bb, and cc directions

GABU, GBCU, GCAU

Shear Moduli in uncompressed configuration in ab, bc, and ca planes

AOPT

Material Axes option 0: Locally orthotropic with material axes determined by element nodes 1, 2, and 4. (Node 1 is the local origin, Node 2 is along the local a- axis; Local c-axis is the cross product of local a-axis, and the vector from node 1 to node 4; Local b- axis is the cross product of loca c- and a- axes.) 1: Locally orthotropic with material axis determined by a point in space, and the global location of the element center; this is the a- direction. This option is for solid elements only. 2: Globally orthotropic with material axis determined by3 vectors below.

XP

x-coordinate of point p, for AOPT = 1

YP

y-coordinate of point p, for AOPT = 1

ZP

z-coordinate of point p, for AOPT = 1

Ai

Component of vector a, for AOPT = 2

Di

Component of vector d, for AOPT = 2

TSEF

Tensile Strain at Element Failure

SSEF

Shear Strain at Element Failure

See Also: • LS-DYNA Keyword User’s Manual

Materials 71 Materials

MAT_RESULTANT_PLASTICITY Defines a resultant formulation material model, including elastoplastic behavior.for beam and shell elements,

Field

Comments

Title

Unique name identifying material model

Desc

Optional description of the material model

TITLE_OPTION

If selected material title option is used

MID

Material identification number (Integer > 0)

RO

Mass Density of the material

E

Young’s Modulus

PR

Poisson’s Ratio

SIGY

Yield Stress

ETAN

Plastic Hardening Modulus (shell elements only)

See Also: • LS-DYNA Keyword User’s Manual

72 Materials

MAT_FORCE_LIMITED This material model allows the simulation of plastic hinge formation at the ends of a beam, using a curve definition (for Belytschko-Schwer beam only).

Field

Comments

Title

Unique name identifying material model

Desc

Optional description of the material model

TITLE_OPTION

If selected material title option is used

MID

Material identification number (Integer > 0)

RO

Mass Density of the material

E

Young’s Modulus

PR

Poisson’s Ratio

DF

Damping Factor

AOPT

Axial Load Curve Option 0: Force vs. Strain 1: Force vs. Change in Length

M1, M2,,,,, M8

Applied end moment for force vs. strain/ or change in length curve. A minimum of one, and a maximum of eight must be defined.

LC1, LC2, ..., LC8

Load Curve Ids applied end moment

Materials 73 Materials

Field

Comments

LPSi

Load Curve Id for plastic moment vs. rotation about s-axis at node i

SFSi

Scale factor, plastic moment vs. rotation about s- axis at node i

YMSi

Yield moment about s- axis at node i for interaction calculations

LPTi

Load Curve Id for plastic moment vs. rotation about t-axis at node i

SFTi

Scale factor, plastic moment vs. rotation about t- axis at node i

YMTi

Yield moment about t- axis at node i for interaction calculations

LPR

Load Curve Id for plastic torsional moment vs. rotation

SFR

Scale factor for plastic torsional moment vs. rotation

YMR

Torsional yield moment for interaction calculations

See Also: • LS-DYNA Keyword User’s Manual MAT_SHAPE_MEMORY Defines the superplastic response present in shape memory alloys (SMA).

Field

Comments

Title

Unique name identifying material model

Desc

Optional description of the material model

TITLE_OPTION

If selected material title option is used

MID

Material identification number (Integer > 0)

RO

Mass Density of the material

E

Young’s Modulus

PR

Poisson’s Ratio

SIG_ASS

Starting value for the forward phase transformation

74 Materials

Field

Comments

SIG_ASF

Final value for the forward phase transformation

SIG_SAS

Starting value for the reverse phase transformations

SIG_SAF

Final value for the reverse phase transformation

EPSL

Recoverable strain or maximum residual strain

ALPHA

Parameter Measuring the difference between material response in tension and compression

YMRT

Young’s Modulus for Martensite

LC_ASS

Load Curve Id for Starting value of forward phase transformation

LC_ASF

Load Curve Id for Final value of forward phase transformation

LC_SAS

Load Curve Id for Starting value of reverse phase transformations

LC_SAF

Load Curve Id for Final value of reverse phase transformation

See Also: • LS-DYNA Keyword User’s Manual MAT_FRAZER_NASH_RUBBER_MODEL Defines rubber from uniaxial test data.

Field

Comments

Title

Unique name identifying material model

Desc

Optional description of the material model

TITLE_OPTION

If selected material title option is used

MID

Material identification number (Integer > 0)

Materials 75 Materials

Field

Comments

RO

Mass Density of the material

PR

Poisson’s Ratio

C100, C200, C300, C400, C110, C210, C010, C020

Strain Energy Parameters

EXIT

Exit option of strain limit 0: Stop if limit exceeds 1: Continue even if limit exceeds

EMAX

Maximum Strain Limit

EMIN

Minimum Strain Limit

REF

Use Reference Geometry to initialize stress tensor 0: Off 1: On

SGL

Specimen Gauge Length

SW

Specimen Width

ST

Specimen Thickness

LCID

Load Curve Id defining Force vs. Actual Change in gauge Length

See Also: • LS-DYNA Keyword User’s Manual

76 Materials

MAT_LAMINATED_GLASS Defines layered glass including polymeric layers.

Field

Comments

Title

Unique name identifying material model

Desc

Optional description of the material model

TITLE_OPTION

If selected material title option is used

MID

Material identification number (Integer > 0)

RO

Mass Density of the material

EG

Young’s Modulus for Glass

PRG

Poisson’s Ratio for Glass

SYG

Yield Strength for Glass

ETG

Plastic Hardening Modulus for Glass

EFG

Plastic Strain at Failure for Glass

EP

Young’s Modulus for Polymer

PRP

Poisson’s Ratio for Polymer

SYP

Yield Strength for Polymer

ETP

Plastic Hardening Modulus for Polymer

NUM_RFS

Number of Integration Points of Material

F1, F2,, ..., FN

Integration Point Material Fi = 0: glass; Fi = 1: polymer

Materials 77 Materials

See Also: • LS-DYNA Keyword User’s Manual MAT_BARLAT_ANISOTROPIC_PLASTICITY Defines the properties of an anisotropic material behavior during forming processes.

Field

Comments

Title

Unique name identifying material model

Desc

Optional description of the material model

TITLE_OPTION

If selected material title option is used

MID

Material identification number (Integer > 0)

RO

Mass Density of the material

E

Young’s Modulus

PR

Poisson’s Ratio

K

Strength Coefficient

E0

Strain corresponding to initial yield

N

Hardening exponent for yield strength

M

Flow potential exponent in Barlat’s model

A, B, C, F, G, H

Anisotropic Coefficients in Barlat’s model

LCID

Load Curve Id defining effective Stress vs. effective Plastic Strain

78 Materials

Field AOPT

Comments Material Axes option 0: Locally orthotropic with material axes determined by element nodes 1, 2, and 4. (Node 1 is the local origin, Node 2 is along the local a- axis; Local c-axis is the cross product of local a-axis, and the vector from node 1 to node 4; Local b- axis is the cross product of loca c- and a- axes.) 1: Locally orthotropic with material axis determined by a point in space, and the global location of the element center; this is the a- direction. This option is for solid elements only. 2: Globally orthotropic with material axis determined by3 vectors below. 3: Locally orthotropic with material axis determined by offsetting the material axes by an angle, OFFANG, from a line defined by the cross product of the vector v with the normal to the plane of a shell element, or mid surface of a brick element.

BETA

Offset angle (for AOPT = 3)

MACF

Material axes change flag for brick element: =1 No Change; = 2 switch mateial axes a and b =3 switch material axes a and c ; =4 switch material axes b and c

XP

X-coordinate of point p for AOPT=1

YP

Y-coordinate of point p for AOPT=1

ZP

Z-coordinate of point p for AOPT=1

Ai

Component of Vector a, for AOPT=2

Vi

Component of Vector v, for AOPT=3

Di

Component of Vector d, for AOPT=2

See Also: • LS-DYNA Keyword User’s Manual

Materials 79 Materials

MAT_BARLAT_YLD96 Defines the properties of an anisotropic material behavior during forming processes, especially for aluminum alloys (only for shell elements only).

Field

Comments

Title

Unique name identifying material model

Desc

Optional description of the material model

TITLE_OPTION

If selected material title option is used

MID

Material identification number (Integer > 0)

RO

Mass Density of the material

E

Young’s Modulus

PR

Poisson’s Ratio

K

Strength Coefficient

E0

Strain corresponding to initial yield

N

Hardening exponent for yield strength

ESRO

εSRO, in power law rate sensitivity

M

Exponent, m for strain rate effects

80 Materials

Field HARD

Comments Hardening option <0: Absolute value defines the Load Curve Id 1:Powerlaw 2: Voce

A

Flow Potential Exponent

Ci

Equation parameters

AX

Equation parameter

AY

Equation Parameter

AZ0

Equation Parameter

AZ1

Equation Parameter

AOPT

Material Axes option 0: Locally orthotropic with material axes determined by element nodes 1, 2, and 4. (Node 1 is the local origin, Node 2 is along the local a- axis; Local c-axis is the cross product of local a-axis, and the vector from node 1 to node 4; Local b- axis is the cross product of loca c- and a- axes.) 1: Locally orthotropic with material axis determined by a point in space, and the global location of the element center; this is the a- direction. This option is for solid elements only. 2: Globally orthotropic with material axis determined by3 vectors below. 3: Locally orthotropic with material axis determined by offsetting the material axes by an angle, OFFANG, from a line defined by the cross product of the vector v with the normal to the plane of the element.

OFFANG

Offset Angle for AOPT = 3

blank1, blank2, blank3

Blank Fields

Ai

Component of Vector a, for AOPT=2

Vi

Component of Vector v, for AOPT=3

Di

Component of Vector d, for AOPT=2

See Also: • LS-DYNA Keyword User’s Manual

Materials 81 Materials

MAT_FABRIC Defines the properties for airbag materials.

Field

Comments

Title

Unique name identifying material model

Desc

Optional description of the material model

TITLE_OPTION

If selected material title option is used

MID

Material identification number (Integer > 0)

RO

Mass Density of the material

EA

Young’s Modulus, Longitudinal Direction

EB

Young’s Modulus, Transverse Direction

EC

Young’s Modulus, Normal Direction

PRBA, PRCA, PRCB

Poisson’s Ratio in ba, ca, and cb directions

GAB, GBC, BCA

Shear Moduli in ab., bc, and ca directions

82 Materials

Field CSE

Comments Compressive Stress Elimination Option 0: Don’t Eliminate 1: Eliminate

EL

Young’s Modulus for Elastic Liner

PRL

Poisson’s Ratio for Elastic Liner

LRATIO

Ratio of linear thickness to total fabric thickness

DAMP

Rayleigh Damping Coefficient

AOPT

Material Axes option 0: Locally orthotropic with material axes determined by element nodes 1, 2, and 4. (Node 1 is the local origin, Node 2 is along the local a- axis; Local c-axis is the cross product of local a-axis, and the vector from node 1 to node 4; Local b- axis is the cross product of loca c- and a- axes.) 1: Locally orthotropic with material axis determined by a point in space, and the global location of the element center; this is the a- direction. This option is for solid elements only. 2: Globally orthotropic with material axis determined by3 vectors below. 3: Locally orthotropic with material axis determined by rotating the material axes about the element normal by an angle, BETA, from a line in the plane of the element defined by the cross product of the vector v with the element normal.

FLC

Fabric Leakage coefficient

FAC

Fabric Area Coefficient

ELA

Effective Leakage Area for blocked fabric

LNRC

Liner Compression Flag 0: Off 1:On

Materials 83 Materials

Field FORM

Comments Flag to modify Membrane Formulation for fabric material: 0: default 1: in variant Local Coordinate System 2: Green-Lagrange strain formulation 3: Large Strain with nonorthogonal material angles 4: Large Strainwith nonorthogonal material angles, and nonlinear material stress strain behavior. Define optional Load Curve Ids.

FVOPT

Fabric Venting Option 1: Wang-Nefske formulas for venting, through orifice, with no blockage. 2: Wang-Nefske formulas for venting through orifice, with blockage. 3: Graefe, Krummheurer, and Siejak [1990] Leakage formulas with no blockage. 4: Graefe, Krummheurer, and Siejak [1990] Leakage formulas with blockage. 5: Leakage formulas based on flow through a porous media, with no blockage. 6: Leakage formulas based on flow through a porous media, with blockage.

TSRFAC

Tensile Stress Cutoff Reduction factor

blank1, blank2, blank3

Blank Fields

Ai

Component of Vector a, for AOPT=2

Vi

Component of Vector v, for AOPT=3

Di

Component of Vector d, for AOPT=2

BETA

Material Angle (Degrees), for AOPT=3

LCA

Load Curve Id for Stress vs. Strain along the a- axis

LCB

Load Curve Id for Stress vs. Strain along the b- axis

LCAB

Load Curve Id for Stress vs. Strain in the ab plane

LCUA

Unload/Reload Curve Id for Stress vs. Strain along a- axis

LCUB

Unload/Reload Curve Id for Stress vs. Strain along b- axis

LCUAB

Unload/Reload Curve Id for Stress vs. Strain in the ab plane

LC_FLC

Load Curve Id for Fabric Leakage Coefficient

84 Materials

Field

Comments

LC_FAC

Load Curve Id for Fabric Area Coefficient

LC_ELA

Load Curve Id for Effective Leakage Area for blocked fabric

LC_TSR

Load Curve Id for Tensile Stress Cutoff Reduction factor vs. Time

See Also: • LS-DYNA Keyword User’s Manual MAT_PLASTIC_GREEN-NAGHDI_RATE This model is available for brick elements only. It is similar to MAT_PLASTIC_KINEMATIC, but uses the Green-Naghdi Rate formulation for the stress update.

Field

Comments

Title

Unique name identifying material model

Desc

Optional description of the material model

TITLE_OPTION

If selected material title option is used

MID

Material identification number (Integer > 0)

RO

Mass Density of the material

E

Young’s Modulus

PR

Poisson’s Ratio

SIGY

Yield Strength

ETAN

Plastic Hardening Modulus

SRC

Strain Rate Parameter

SRP

Strain Rate Parameter

BETA

Hardening Parameter

See Also: • LS-DYNA Keyword User’s Manual

Materials 85 Materials

MAT_3-PARAMETER_BARLAT This material model is designed for modeling sheets with anisotropic materials under plane stress conditions.

Field

Comments

Title

Unique name identifying material model

Desc

Optional description of the material model

TITLE_OPTION

If selected material title option is used

MID

Material identification number (Integer > 0)

RO

Mass Density of the material

E

Young’s Modulus

PR

Poisson’s Ratio

HR

Hardening Rule 1: Linear 2: Exponential 3: Load Curve

P1, P2

Material Parameters

86 Materials

Field ITER

Comments Iteration Flag 0: Fully iterative 1: Fixed to 3 iterations

M

Exponent in Barlat’s yield surface

R00, R45, R90

Lankford Parameters

LCID

Load Curve Id for hardening rule

Epsilon_0

ε0 for determining initial yield stress for exponential hardening

SPI

Parameter to redefine ε0

AOPT

Material Axes option 0: Locally orthotropic with material axes determined by element nodes 1, 2, and 4. (Node 1 is the local origin, Node 2 is along the local a- axis; Local c-axis is the cross product of local a-axis, and the vector from node 1 to node 4; Local b- axis is the cross product of loca c- and a- axes.) 1: Locally orthotropic with material axis determined by a point in space, and the global location of the element center; this is the a- direction. This option is for solid elements only. 2: Globally orthotropic with material axis determined by3 vectors below. 3: Locally orthotropic with material axis determined by rotating the material axes about the element normal by an angle, BETA, from a line in the plane of the element defined by the cross product of the vector v with the element normal.

blank1, blank2, blank3

Blank Fields

XP

X-coordinate of point p for AOPT=1

YP

Y-coordinate of point p for AOPT=1

ZP

Z-coordinate of point p for AOPT=1

Ai

Component of Vector a, for AOPT=2

Vi

Component of Vector v, for AOPT=3

Di

Component of Vector d, for AOPT=2

BETA

Material Angle (Degrees), for AOPT=3

See Also: • LS-DYNA Keyword User’s Manual

Materials 87 Materials

MAT_TRANS_ANISO_ELASPLASTIC Simulates sheet forming processes with anisotropic material. Only transverse anisotropy can be considered.

Field

Comments

Title

Unique name identifying material model

Desc

Optional description of the material model

TITLE_OPTION

If selected material title option is used

MID

Material identification number (Integer > 0)

RO

Mass Density of the material

E

Young’s Modulus

PR

Poisson’s Ratio

SIGY

Yield Stress

ETAN

Plastic Hardening Modulus

R

Anisotropic Hardening Parameter

HLCID

Load Curve Id for Effective Yield Stress vs. Effective Plastic Strain

See Also: • LS-DYNA Keyword User’s Manual

88 Materials

MAT_TRANS_ANISO_ELASPLASTIC_ECHANGE Simulates sheet forming processes with anisotropic material. Only transverse anisotropy can be considered.

Field

Comments

Title

Unique name identifying material model

Desc

Optional description of the material model

TITLE_OPTION

If selected material title option is used

MID

Material identification number (Integer > 0)

RO

Mass Density of the material

E

Young’s Modulus

PR

Poisson’s Ratio

SIGY

Yield Stress

ETAN

Plastic Hardening Modulus

R

Anisotropic Hardening Parameter

HLCID

Load Curve Id for Effective Yield Stress vs. Effective Plastic Strain

IDSCALE

Load curve Id defining the scale factor for Young’s modulus change with respect to effective strain. Note: if EA, and COE are defined, this curve is not necessary.

EA, COE

Coefficients (EA and ζ) defining Young’s modulus with respect to the effective strain. Note: if EA, and COE are defined, this curve is not necessary.

See Also: • LS-DYNA Keyword User’s Manual

Materials 89 Materials

MAT_BLATZ-KO_FOAM Defines the properties for rubber like foams of polyurethane. It is a simple one parameter model with a fixed Poisson’s ratio of 0.25.

Field

Comments

Title

Unique name identifying material model

Desc

Optional description of the material model

TITLE_OPTION

If selected material title option is used

MID

Material identification number (Integer > 0)

RO

Mass Density of the material

G

Shear Modulus

REF

Use Reference Geometry to initialize stress tensor

See Also: • LS-DYNA Keyword User’s Manual

90 Materials

MAT_FLD_TRANSVERSELY_ANISOTROPIC Simulates sheet forming processes with anisotropic material. Only transverse anisotropy can be considered.

Field

Comments

Title

Unique name identifying material model

Desc

Optional description of the material model

TITLE_OPTION

If selected material title option is used

MID

Material identification number (Integer > 0)

RO

Mass Density of the material

E

Young’s Modulus

PR

Poisson’s Ratio

SIGY

Yield Stress

ETAN

Plastic Hardening Modulus

R

Anisotropic Hardening Modulus

HLCID

Load Curve Id defining Effective Yield Stress vs. Effective Plastic Strain

LCIDFLD

Load Curve Id defining the Forming Limit Diagram (major vs. minor strain)

See Also: • LS-DYNA Keyword User’s Manual

Materials 91 Materials

MAT_NONLINEAR_ORTHOTROPIC Defines an orthotropic nonlinear elastic material based on a finite strain formulation with initial geometry as the reference. Optional failure and stiffness properties are available.

Field

Comments

Title

Unique name identifying material model

Desc

Optional description of the material model

TITLE_OPTION

If selected material title option is used

MID

Material identification number (Integer > 0)

RO

Mass Density of the material

EAA, EBB, ECC

Young’s Modulus in the A, B and C directions

PRBA, PRCA, PRCB

Poisson’s Ratio in the ba, ca and cb directions

GAB, GBC, GCA

Shear Modulus in the ab, bc and ca directions

DT

Temperature increment for stress stabilization

TRAMP

Time to ramp up to the final temperature

ALPHA

Thermal expansion coefficient

LCIDA, LCIDB, LCIDC Load Curve Id for nominal stress vs. nominal strain in the a- , b-, and c-axes EFAIL

Failure Strain

92 Materials

Field

Comments

DTFAIL

Timestep size criteria for element erosion

CDAMP

Damping Coefficient

AOPT

Material Axes option 0: Locally orthotropic with material axes determined by element nodes 1, 2, and 4. (Node 1 is the local origin, Node 2 is along the local a- axis; Local c-axis is the cross product of local a-axis, and the vector from node 1 to node 4; Local b- axis is the cross product of loca c- and a- axes.) 1: Locally orthotropic with material axis determined by a point in space, and the global location of the element center; this is the a- direction. This option is for solid elements only. 2: Globally orthotropic with material axis determined by3 vectors below. 3: Locally orthotropic with material axis determined by rotating the material axes about the element normal by an angle, BETA, from a line in the plane of the element defined by the cross product of the vector v with the element normal.

blank1, blank2, blank3

Blank Fields

Ai

Component of Vector a, for AOPT=2

Vi

Component of Vector v, for AOPT=3

Di

Component of Vector d, for AOPT=2

BETA

Material Angle (Degrees), for AOPT=3

LCIDAB, LCIDBC, LCIDCA

Load Curve Id for nominal shear stress vs. nominal shear strain in the ab, bc, and ca plane

See Also: • LS-DYNA Keyword User’s Manual

Materials 93 Materials

MAT_BAMMAN Defines a material with temperature and rate dependent plasticity.

Field

Comments

Title

Unique name identifying material model

Desc

Optional description of the material model

TITLE_OPTION

If selected material title option is used

MID

Material identification number (Integer > 0)

RO

Mass Density of the material

E

Young’s Modulus

PR

Poisson’s Ratio

T

Initial Temperature

HC

Heat Generation Coefficient

Ci

Input parameters

Ai

Initial value of state variable i

KAPPA

Initial value of internal state variable 6 (κ)

See Also: • LS-DYNA Keyword User’s Manual

94 Materials

MAT_BAMMAN_DAMAGE Defines a material with temperature and rate dependent plasticity including damage in the modeling.

Field

Comments

Title

Unique name identifying material model

Desc

Optional description of the material model

TITLE_OPTION

If selected material title option is used

MID

Material identification number (Integer > 0)

RO

Mass Density of the material

E

Young’s Modulus

PR

Poisson’s Ratio

T

Initial Temperature

HC

Heat Generation Coefficient

Ci

Input parameter

Ai

Initial value of state variable i

N

Exponent in damage evaluation

D0

Initial Damage (porosity)

FS

Failure Strain for Erosion

Materials 95 Materials

See Also: • LS-DYNA Keyword User’s Manual MAT_CLOSED_CELL_FOAM Defines a low density, closed polyurethane foam for simulating impact limiters in automotive applications.

Field

Comments

Title

Unique name identifying material model

Desc

Optional description of the material model

TITLE_OPTION

If selected material title option is used

MID

Material identification number (Integer > 0)

RO

Mass Density of the material

E

Young’s Modulus

PR

Poisson’s Ratio

A, B, C

Factors a, b, and c for Yield Stress definition

P0

Initial Foam Pressure

PHI

Ratio of Foam to Polymer Density

GAMA0

Initial Volumetric Strain

LCID

Load Curve Id defining vonMises Stress vs. Volumetric Strain

See Also: • LS-DYNA Keyword User’s Manual

96 Materials

MAT_ENHANCED_COMPOSITE_DAMAGE Defines the properties of an orthrotropic material with optional brittle failure for composites. This is an enhanced version of MAT_COMPOSITE_DAMAGE (MAT_022).

Field

Comments

Title

Unique name identifying material model

Desc

Optional description of the material model

TITLE_OPTION

If selected material title option is used

MID

Material identification number (Integer > 0)

RO

Mass Density of the material

EA

Young’s Modulus, Longitudinal Direction

EB

Young’s Modulus, Transverse Direction

EC

Young’s Modulus, Normal Direction (NOT used)

PRBA, PRCA, PRCB

Poisson’s Ratio in the ba, ca, and cb planes (PRCA, PRCB NOT used)

GAB, GBC, GCA

Shear Modulus in the ab, bc, and ca planes

KF

Bulk Modulus of failed material (NOT used)

Materials 97 Materials

Field AOPT

Comments Material Axes option 0: Locally orthotropic with material axes determined by element nodes 1, 2, and 4. (Node 1 is the local origin, Node 2 is along the local a- axis; Local c-axis is the cross product of local a-axis, and the vector from node 1 to node 4; Local b- axis is the cross product of loca c- and a- axes.) 1: Locally orthotropic with material axis determined by a point in space, and the global location of the element center; this is the a- direction. This option is for solid elements only. 2: Globally orthotropic with material axis determined by3 vectors below. 3: Locally orthotropic with material axis determined by rotating the material axes about the element normal by an angle, BETA, from a line in the plane of the element defined by the cross product of the vector v with the element normal.

bl1, bl2, bl3

Blank Fields

Ai

Components of Vector a, for AOPT=2

MANGLE

Material Angle (Degrees), for AOPT=3

Vi

Components of Vector v, for AOPT=3

Di

Component of Vector d, for AOPT=2

DFAILM

Maximum Strain for matrix straining in tension/compression

DFAILS

Maximum shear strain

TFAIL

Timestep size criteria for element deletion

ALPH

Shear Stress Parameter for NonLinear Term

SOFT

Softening Reduction Factor

FBRT

Softening of fiber Tensile Strength

YCFAC

Reduction Factor for compressive fiber strength, after matrix failure

DFAILT

Maximum Strain for fiber in tension

DFAILC

Maximum Strain for fiber in compression

EFS

Effective Failure Strain

XC

Longitudinal Compression Strength

XT

Longitudinal Tensile Strength

YC

Transverse Compression Strength

YT

Transverse Tensile Strength

SC

Shear Strength, ab plane

98 Materials

Field CRIT

Comments Failure Criteria (Material Number) 54: Chang matrix failure criterion 55: Tsai-Wu matrix failure criterion

BETA

Weight Factor for Shear term in tensile fiber mode

See Also: • LS-DYNA Keyword User’s Manual

Materials 99 Materials

MAT_LAMINATED_COMPOSITE_FABRIC Defines a composite material with unidirectional layers, complete laminates and woven fabrics (for shell elements only).

Field

Comments

Title

Unique name identifying material model

Desc

Optional description of the material model

TITLE_OPTION

If selected material title option is used

MID

Material identification number (Integer > 0)

RO

Mass Density of the material

EA

Young’s Modulus, Longitudinal Direction

EB

Young’s Modulus, Transverse Direction

EC

Young’s Modulus, Normal Direction (NOT used)

PRBA

Poisson’s Ratio in BA direction

100 Materials

Field

Comments

TAU1

Stress limit of first slightly nonlinear part of Shear Stress vs. Shear Strain curve

GAMMA1

Strain limit of first slightly nonlinear part of Shear Stress vs. Shear Strain curve

SLIMT1

Factor to determine the minimum Stress Limit after Stress Maximum (fiber Tension)

SLIMC1

Factor to determine the minimum Stress Limit after Stress Maximum (fiber Compression)

SLIMS

Factor to determine the minimum Stress Limit after Stress Maximum (Shear)

AOPT

Material Axes option 0: Locally orthotropic with material axes determined by element nodes 1, 2, and 4. (Node 1 is the local origin, Node 2 is along the local a- axis; Local c-axis is the cross product of local a-axis, and the vector from node 1 to node 4; Local b- axis is the cross product of loca c- and a- axes.) 1: Locally orthotropic with material axis determined by a point in space, and the global location of the element center; this is the a- direction. This option is for solid elements only. 2: Globally orthotropic with material axis determined by3 vectors below. 3: Locally orthotropic with material axis determined by rotating the material axes about the element normal by an angle, BETA, from a line in the plane of the element defined by the cross product of the vector v with the element normal.

TSIZE

Time step size for Automatic Element Deletion

ERODS

Maximum Element Strain for Element Layer Failure

SOFT

Softening Reduction Factor in Crash front

FS

Failure Surface Type 1: Smooth surface Failure with Quadratic criteria for both fiber and transverse directions 0: Smooth surface Failure with Quadratic criteria for transverse direction, with a limiting value in the fiber direction -1: Faceted Failure surface

XP

X-coordinate of point p for AOPT=1

YP

Y-coordinate of point p for AOPT=1

Materials 101 Materials

Field

Comments

ZP

Z-coordinate of point p for AOPT=1

Ai

Component of Vector a, for AOPT=2

Vi

Component of Vector v, for AOPT=3

Di

Component of Vector d, for AOPT=2

BETA

Material Angle (Degrees), for AOPT=3

E11C

Strain at Longitudinal Compression Strength, a-axis

E11T

Strain at Longitudinal Tensile Strength, a-axis

E22C

Strain at Transverse Compression Strength, b-axis

E22T

Strain at Transverse Tensile Strength, b-axis

GMS

Strain at Shear Strength, ab plane

XC

Longitudinal Compression Strength

XT

Longitudinal Tensile Strength

YC

Transverse Compression Strength, b-axis

YT

Transverse Tensile Strength, b-axis

SC

Shear Strength, ab plane

See Also: • LS-DYNA Keyword User’s Manual

102 Materials

MAT_COMPOSITE_FAILURE_SHELL_MODEL Defines the properties of a composite material with failure properties (for shell elements only).

Field

Comments

Title

Unique name identifying material model

Desc

Optional description of the material model

TITLE_OPTION

If selected material title option is used

MID

Material identification number (Integer > 0)

RO

Mass Density of the material

EA

Young’s Modulus, Longitudinal Direction

EB

Young’s Modulus, Transverse Direction

EC

Young’s Modulus, Normal Direction

PRBA, PRCA< PRCB

Poisson’s Ratio in ba, ca and cb directions

GAB, GBC, GCA

Shear Moduli in ab, bc and ca directions

KF

Bulk Modulus of failed material

Materials 103 Materials

Field AOPT

Comments 0: Locally orthotropic with material axes determined by element nodes 1, 2, and 4. (Node 1 is the local origin, Node 2 is along the local a- axis; Local c-axis is the cross product of local a-axis, and the vector from node 1 to node 4; Local b- axis is the cross product of loca c- and a- axes.) 1: Locally orthotropic with material axis determined by a point in space, and the global location of the element center; this is the a- direction. This option is for solid elements only. 2: Globally orthotropic with material axis determined by3 vectors below. 3: Locally orthotropic with material axis determined by rotating the material axes about the element normal by an angle, BETA, from a line in the plane of the element defined by the cross product of the vector v with the element normal.

MAFLAG

Material Axes Flag (NOT active for shells)

XP

X-coordinate of point p for AOPT=1 and 4

YP

Y-coordinate of point p for AOPT=1 and 4

ZP

Z-coordinate of point p for AOPT=1and 4

Ai

Component of Vector a, for AOPT=2

Vi

Component of Vector v, for AOPT=3, and 4

Di

Component of Vector d, for AOPT=2

BETA

Material Angle (Degrees), for AOPT=3

TSIZE

Time step size for Automatic Element Deletion

ALP

Nonlinear stress parameter

SOFT

Softening Reduction Factor in Crashfront

FBRT

Softening of fiber Tensile Strength

SR

Reduction Factor

SF

Softening Factor

XC

Longitudinal Compression Strength

XT

Longitudinal Tensile Strength

YC

Transverse Compression Strength, b-axis

YT

Transverse Tensile Strength, b-axis

SC

Shear Strength, ab plane

See Also: • LS-DYNA Keyword User’s Manual

104 Materials

MAT_COMPOSITE_FAILURE_SOLID_MODEL Defines the properties of a composite material with failure properties (for solid elements only).

Field

Comments

Title

Unique name identifying material model

Desc

Optional description of the material model

TITLE_OPTION

If selected material title option is used

MID

Material identification number (Integer > 0)

RO

Mass Density of the material

EA

Young’s Modulus, Longitudinal Direction

EB

Young’s Modulus, Transverse Direction

EC

Young’s Modulus, Normal Direction

PRBA, PRCA< PRCB

Poisson’s Ratio in ba, ca and cb directions

GAB, GBC, GCA

Shear Moduli in ab, bc and ca directions

KF

Bulk Modulus of failed material

Materials 105 Materials

Field AOPT

Comments Material Axes option 0: Locally orthotropic with material axes determined by element nodes 1, 2, and 4. (Node 1 is the local origin, Node 2 is along the local a- axis; Local c-axis is the cross product of local a-axis, and the vector from node 1 to node 4; Local b- axis is the cross product of loca c- and a- axes.) 1: Locally orthotropic with material axis determined by a point in space, and the global location of the element center; this is the a- direction. This option is for solid elements only. 2: Globally orthotropic with material axis determined by3 vectors below. 3: Locally orthotropic with material axis determined by rotating the material axes about the element normal by an angle, BETA, from a line in the plane of the element defined by the cross product of the vector v with the element normal. 4: Locally orthotropic in cylindrical coordinate system with the material axis determined by a vector v, and an originating point, P, which defines the centerline axis. This option is for solid elements only.

MAFLAG

Material Axes Change Flag 1: Default 2: Switch Axes a and b 3: Switch Axes a and c

XP

X-coordinate of point p for AOPT=1 and 4

YP

Y-coordinate of point p for AOPT=1 and 4

ZP

Z-coordinate of point p for AOPT=1and 4

Ai

Component of Vector a, for AOPT=2

Vi

Component of Vector v, for AOPT=3, and 4

Di

Component of Vector d, for AOPT=2

BETA

Material Angle (Degrees), for AOPT=3

SBA

In Plane Shear Strength

SCA

Transverse Shear Strength

SCB

Transverse Shear Strength

XXC

Longitudinal Compression Strength, x-axis

YYC

Transverse Compression Strength, b-axis

106 Materials

Field

Comments

ZZC

Normal Compression Strength, c-axis

XXT

Longitudinal Tensile Strength, x-axis

YYT

Transverse Tensile Strength, b-axis

ZZT

Normal Tensile Strength, c-axis

See Also: • LS-DYNA Keyword User’s Manual MAT_ELASTIC_WITH_VISCOSITY Simulates the forming of glass products at high temperatures.

Field

Comments

Title

Unique name identifying material model

Desc

Optional description of the material model

TITLE_OPTION

If selected material title option is used

MID

Material identification number (Integer > 0)

Materials 107 Materials

Field RO

Comments Mass Density of the material

V0 A, B, C

Viscosity coefficients

LCID

Load Curve Id defining factor for viscosity vs. temperature

PRi Ti

Temperatures

Vi

Corresponding Viscosity coefficients

Ei

Corresponding Young’s moduli coefficients

ALPHAi

Corresponding thermal expansion coefficients

See Also: • LS-DYNA Keyword User’s Manual MAT_ELASTIC_WITH_VISCOSITY_CURVE Simulates the forming of glass products at high temperatures.Load curves are used to represent the temperature dependence of Poisson’s ratio, Young’s modulus, the coefficient of thermal expansion, and the viscosity.

Field

Comments

Title

Unique name identifying material model

Desc

Optional description of the material model

TITLE_OPTION

If selected material title option is used

MID

Material identification number (Integer > 0)

RO

Mass Density of the material

V0

108 Materials

Field

Comments

A, B, C

Viscosity coefficients

LCID

Load Curve Id defining factor for viscosity vs. temperature

PR_LC

Load curve defining Poisson’s ratio as a function of temperature

YM_LC

Load curve defining Young’s modulus as a function of temperature

A_LC

Load curve defining the coefficient of thermal expansion as a function of temperature

V_LC

Load curve defining the viscosity as a function of temperature

V_LOG

Falg for the form of V_LC. If V_LOg =1, the value specified in V_LC is the natural logarithm of the viscosity. If V_LOg =0, the value is the viscosity.

See Also: • LS-DYNA Keyword User’s Manual MAT_KELVIN-MAXWELL_VISCOELASTIC A classic Kelvin-Maxwell material model for modeling viscoelastic bodies, like foams.

Field

Comments

Title

Unique name identifying material model

Desc

Optional description of the material model

TITLE_OPTION

If selected material title option is used

MID

Material identification number (Integer > 0)

RO

Mass Density of the material

BULK

Bulk Modulus (elastic)

GO

Short time Shear Modulus

GI

Long time Shear Modulus

DC

Maxwell decay constant or Kelvin relaxation constant

Materials 109 Materials

Field FO

Comments Formulation option 0: Maxwell 1: Kelvin

SO

Strain output option 0: Maximum principal Strain occurring during the calculation 1: Maximum magnitude of principal Strain occurring during the calculation 2: Maximum Effective Strain occurring during the calculation

See Also: • LS-DYNA Keyword User’s Manual MAT_VISCOUS_FOAM A material to represent the Confor Foam on the ribs of EuroSID side impact dummy (valid only for solid elements under compressive load).

Field

Comments

Title

Unique name identifying material model

Desc

Optional description of the material model

TITLE_OPTION

If selected material title option is used

MID

Material identification number (Integer > 0)

RO

Mass Density of the material

E1

Initial Young’s Modulus

N1

Exponent in power law for Young’s Modulus

V2

Viscous Coefficient

E2

Elastic Modulus for viscosity

110 Materials

Field

Comments

N2

Exponent in power law for viscosity

PR

Poisson’s Ratio

See Also: • LS-DYNA Keyword User’s Manual MAT_CRUSHABLE_FOAM A material model for modeling crushable foam with optional damping and tension cutoff.

Field

Comments

Title

Unique name identifying material model

Desc

Optional description of the material model

TITLE_OPTION

If selected material title option is used

MID

Material identification number (Integer > 0)

RO

Mass Density of the material

E

Young’s Modulus

PR

Poisson’s Ratio

LCID

Load Curve Id defining Yield Stress vs. Volumetric Strain

TSC

Tensile Stress Cutoff

DAMP

Rate sensitivity via damping coefficient

See Also: • LS-DYNA Keyword User’s Manual

Materials 111 Materials

MAT_RATE_SENSITIVE_POWERLAW_PLASTICITY A strain rate sensitive elasto-plastic material model with a power law hardening.

Field

Comments

Title

Unique name identifying material model

Desc

Optional description of the material model

TITLE_OPTION

If selected material title option is used

MID

Material identification number (Integer > 0)

RO

Mass Density of the material

E

Young’s Modulus

PR

Poisson’s Ratio

K

Material Constant

M

Strain Hardening Coefficient

N

Strain Rate Sensitivity Coefficient

E0

Initial Strain Rate

VP

Formulation for Rate Effects 0: Scale Yield Stress 1: ViscoPlastic Formulation

EPSO

Factor to Normalize Strain (Time Units) 1: Seconds 1e-006 : Milliseconds 1e-006 : Microseconds

112 Materials

Field

Comments

LCID_K

Load Curve Id defining material constant K vs. Effective Plastic Strain

LCID_M

Load Curve Id defining material constant M vs. Effective Plastic Strain

LCID_N

Load Curve Id defining material constant N vs. Effective Plastic Strain

See Also: • LS-DYNA Keyword User’s Manual MAT_MODIFIED_ZERILLI_ARMSTRONG A rate and temperature sensitive plasticity material model, sometimes used in ordinance design calculations.

Field

Comments

Title

Unique name identifying material model

Desc

Optional description of the material model

TITLE_OPTION

If selected material title option is used

MID

Material identification number (Integer > 0)

RO

Mass Density of the material

G

Shear Modulus

E0

Factor to normalize strain rate

N

Exponent for bcc metal

TROOM

Room Temperature

PC

Pressure Cutoff

Materials 113 Materials

Field SPALL

Comments Spall Type 1: Minimum Pressure Limit 2: Maximum Principal Stress 3: Minimum Pressure Cutoff

Ci

Coefficients for flow stress

EFAIL

Failure Strain for Erosion

VP

Formulation for Rate Effects 0: Scale Yield Stress 1: ViscoPlastic Formulation

Bi

Coefficients for polynomial representation of temperature dependency of flow stress yield

Gi

Coefficient for defining Heat Capacity and temperature dependency of Heat Capacity

BULK

Bulk Modulus (for shell elements only)

See Also: • LS-DYNA Keyword User’s Manual

114 Materials

MAT_LINEAR_ELASTIC_DISCRETE_BEAM A material model for linear elastic beams by using six springs each acting along one of its six degrees of freedom. The two nodes that define the beam can be coincident to give a zero length beam, or offset to give a finite length beam.

Field

Comments

Title

Unique name identifying material model

Desc

Optional description of the material model

TITLE_OPTION

If selected material title option is used

MID

Material identification number (Integer > 0)

RO

Mass Density of the material

TKR, TKS, TKT

Translational Stiffness along local ar-, s-, and t- axes respectively

RKR, RKS, RKT

Rotational Stiffness about local r-, s-, and t- axes respectively

TDR, TDS, TDT

Translational viscous damping along local r-, s-, and t- axes respectively

RDR, RDS, RDT

Rotational viscous damping about local r-, s-, and t- axes respectively

FOR, FOS, FOT

Pre-load forces in r-, s- and t-directions repectively (optional)

MOR, MOS, MOT

Pre-load moments in r-, s- and t-directions repectively (optional)

See Also: • LS-DYNA Keyword User’s Manual

Materials 115 Materials

MAT_NONLINEAR_ELASTIC_DISCRETE_BEAM A material model for nonlinear elastic and nonlinear viscous beams by using six springs each acting along one of its six degrees of freedom. The two nodes that define the beam can be coincident to give a zero length beam, or offset to give a finite length beam.

Field

Comments

Title

Unique name identifying material model

Desc

Optional description of the material model

TITLE_OPTION

If selected material title option is used

MID

Material identification number (Integer > 0)

RO

Mass Density of the material

LCIDTR, LCIDTS, LCIDTT

Load Curve Id defining Translational Force along the r-, s-, and t- axes vs. Translational Displacement

LCIDRR, LCIDRS, LCIDRT

Load Curve Id defining Rotational Moment about the r-, s-, and t- axes vs. Rotational Displacement

LCIDTDR, LCIDTDS, LCIDTDT

Load Curve Id defining Translational Damping Force along the r-, s-, and t- axes vs. Translational Velocity

LCIDRDR, LCIDRDS, LCIDRDT

Load Curve Id defining Rotational Damping Force the r-, s-, and t- axes axis vs. Rotational Velocity

FOR, FOS, FOT

Pre-load forces in r-, s- and t-directions repectively (optional)

MOR, MOS, MOT

Pre-load moments in r-, s- and t-directions repectively (optional)

See Also: • LS-DYNA Keyword User’s Manual

116 Materials

MAT_NONLINEAR_PLASTIC_DISCRETE_BEAM A a material model for nonlinear elastoplastic, linear viscous behavior of beams by using six springs each acting along one of its six degrees of freedom. The two nodes that define the beam can be coincident to give a zero length beam, or offset to give a finite length beam.

Field

Comments

Title

Unique name identifying material model

Desc

Optional description of the material model

TITLE_OPTION

If selected material title option is used

MID

Material identification number (Integer > 0)

RO

Mass Density of the material

TKR, TKS, TKT

Translational Stiffness along local r-, s-, and t- axes respectively

RKR, RKS, RKT

Rotational Stiffness about local r-, s-, and t- axes respectively

TDR, TDS, TDT

Translational viscous damping along local r-, s-, and t- axes respectively

RDR, RDS, RDT

Rotational viscous damping about local r-, s-, and t- axes respectively

LCPDR, LCPDS, LCPDT

Load Curve Id for Yield Force vs. Plastic Displacement along local r-, s-, and t- axes respectively

LCPMR, LCPMS, LCPMT

Load Curve Id for Yield Moment vs. Plastic Rotation about local r-, s-, and t- axes respectively

Materials 117 Materials

Field

Comments

FFAILR, FAILS, FAILT

Failure Parameters corresponding to Force Fr, Fs, Ft

MFAILR, MFAILS, MFAILT

Failure Parameters corresponding to Moment Mr, Ms, Mt

UFAILR, UFAILS, UFAILT

Failure Parameters corresponding to Displacement Ur, Us, Ut

TFAILR, TFAILS, TFAILT

Failure Parameters corresponding to Rotation θr, θs, θt

FOR, FOS, FOT

Pre-load forces in r-, s- and t-directions repectively (optional)

MOR, MOS, MOT

Pre-load moments in r-, s- and t-directions repectively (optional)

See Also: • LS-DYNA Keyword User’s Manual MAT_SID_DAMPER_DISCRETE_BEAM A material model for side impact dummy, using a damper that is not adequately taken care of by the nonlinear force versus relative velocity curves.

Field

Comments

Title

Unique name identifying material model

Desc

Optional description of the material model

TITLE_OPTION

If selected material title option is used

MID

Material identification number (Integer > 0)

118 Materials

Field

Comments

RO

Mass Density of the material

ST

Piston Stroke

D

Piston Diameter

R

Orifice Radius

H

Orifice Controller Position

K

Damping Constant

C

Discharge Coefficient

C3

Coefficient for fluid inertia term

STF

Stiffness Coefficient (piston bottom out)

RHOF

Fluid Density

C1

Coefficient of linear velocity term

C2

Coefficient of quadratic velocity term

LCIDF

Load Curve Id defining Force vs. Piston Displacement

LCIDD

Load Curve Id defining Damping Coefficient vs. Piston Displacement

S0

Initial Displacement

NUM_RFS

Number of Orifice Location

ORFLOCi

Orifice Location of the i-th orifice, relative to the fix end

ORFRADi

Orifice Radius of the i-th orifice

SFi

Scale factor on calculated force for the i-th orifice

DCi

Linear viscous damping coefficient (after damper bottoms out in tension or compression) for the i-th orifice

See Also: • LS-DYNA Keyword User’s Manual

Materials 119 Materials

MAT_HYDRAULIC_GAS_DAMPER_DISCRETE_BEAM A special element that represents a combined hydraulic and gas-filled damper with a variable orifice coefficient. This material can only be used as a discrete beam element.

Field

Comments

Title

Unique name identifying material model

Desc

Optional description of the material model

TITLE_OPTION

If selected material title option is used

MID

Material identification number (Integer > 0)

RO

Mass Density of the material

C0

Length of Gas Column

N

Adiabatic constant

P0

Initial gas Pressure

PA

Atmospheric Pressure

AP

Piston Cross-Section Area

KH

Hydraulic Constant

LCID

Load Curve Id Defining Orifice Area vs. Element Deletion

FR

Return factor on orifice force

SCLF

Scale factor on Force

CLEAR

Clearance

See Also: • LS-DYNA Keyword User’s Manual

120 Materials

MAT_CONCRETE_DAMAGE A material model for analyzing buried steel reinforced concrete structure with impulsive loading.

Field

Comments

Title

Unique name identifying material model

Desc

Optional description of the material model

TITLE_OPTION

If selected material title option is used

MID

Material identification number (Integer > 0)

RO

Mass Density of the material

E

Young’s Modulus

PR

Poisson’s Ratio

SIGF

Maximum principal Stress at Failure

A0, A0Y

Cohesion and Cohesion for Yield

Materials 121 Materials

Field

Comments

A1, A2

Pressure Hardening Coefficients

A1Y, A2Y

Pressure Hardening Coefficients for yield limit

A1F, A2F

Pressure Hardening Coefficients Failed Material)

B1

Damage Scaling Factor

B2

Damage Scaling Facto for uniaxial tensile path

B3

Damage Scaling Facto for triaxial tensile path

PER

Percent Reinforcement

ER

Young’s Modulus for Reinforcement

PRR

Poisson’s Ration for Reinforcement

SIGY

Initial Yield Stress

ETAN

Tangent Modulus/Plastic hardening Modulus

LCP

Load Curve Id giving rate sensitivity for principal material

LCR

Load Curve Id giving rate sensitivity for reinforcement

LAMBDAi

Tabulated Damage functions

ETAi

Tabulated Scale Factors

See Also: • LS-DYNA Keyword User’s Manual

122 Materials

MAT_LOW_DENSITY_VISCOUS_FOAM A material model for low density urethane foam with high compressibility, and with rate sensitivity characterized by a relaxation curve.

Field

Comments

Title

Unique name identifying material model

Desc

Optional description of the material model

TITLE_OPTION

If selected material title option is used

MID

Material identification number (Integer > 0)

RO

Mass Density of the material

E

Young’s Modulus

LCID

Load Curve Id for nominal Stress vs. Strain

TC

Tension Cutoff Stress

HU

Hysteretic Unloading Factor between 0 to 1

BETA

Decay constant to model creep in unloading

DAMP

Viscous coefficient

SHAPE

Shape factor for unloading

FAIL

Failure Option after Cutoff Stress 1: Tensile stress remains at cutoff value 2: Tensile stress is reset to zero

Materials 123 Materials

Field BVFLAG

Comments Bulk Viscosity activation Flag 0: No 1: Active

KCON

Stiffness coefficient for contact interface stiffness

LCID2

Load Curve Id of relaxation curve

BSTART

Fit Parameter

TRAMP

Optional ramp time for loading

NV

Number of terms in fit

NUM_RFS

Number of viscoelastic constants

GI1

Optional relaxation modulus for rate effect

BETAI1

Optional decay constant

REF

Use Reference Geometry to initialize stress tensor 0: Off 1: On

See Also: • LS-DYNA Keyword User’s Manual MAT_ELASTIC_SPRING_DISCRETE_BEAM A model for elastic springs with damping to be combined and represented with a discrete beam element.

Field

Comments

Title

Unique name identifying material model

Desc

Optional description of the material model

124 Materials

Field

Comments

TITLE_OPTION

If selected material title option is used

MID

Material identification number (Integer > 0)

RO

Mass Density of the material

E

Young’s Modulus

K

Elastic loading and unloading stiffness

F0

Optional initial force

D

Optional viscous damping coefficient

CDF

Compressive displacement at failure

TDF

Tensile displacement at failure

FLCID

Load Curve Id defining Yield Force vs. Deflection for nonlinear behavior

HLCID

Load Curve Id defining Force vs. Relative Velocity for nonlinear behavior

Ci

Damping Coefficients

DLE

Scale factor for time unit

GLCID

Load Curve Id defining Scale Factor vs. Deflection for Load Curve Id (HLCID)

See Also: • LS-DYNA Keyword User’s Manual MAT_BILKHU/DUBOIS_FOAM A material model to simulate isotropic crushable foams using uniaxial and triaxial test data.

Field

Comments

Title

Unique name identifying material model

Desc

Optional description of the material model

Materials 125 Materials

Field

Comments

TITLE_OPTION

If selected material title option is used

MID

Material identification number (Integer > 0)

RO

Mass Density of the material

YM

Young’s Modulus

LCPY

Load Curve Id defining Yield Pressure vs. Volumetric Strain

LCUYS

Load Curve Id defining uniaxial Yield Stress vs. Volumetric Strain

VC

Viscous Damping Coefficient

PC

Pressure Cutoff

VPC

Variable Pressure Cutoff as a fraction of pressure yield value

TC

Tension Cutoff for uniaxial tensile stress

VTC

Variable Tension Cutoff as a fraction of uniaxial compressive yield strength

LCRATE

Load Curve Id defining Scale Factor for the previous yield curves, dependent upon the volumetric strain vs. Volumetric plastic Strain

PR

Poisson coefficient applying to both elastic and plastic deformations

KCON

Stiffness coefficient for contact interface stiffness. If undefined, one third of Young’s Modulus (YM) is used..

ISFLG

Tensile response flag (active only if negative abscissa are present in the load curve LCUYS). .EQ. 0: load curve abscissa in tensile region correspond to volumetric strain. .EQ. 1: load curve abscissa in tensile region correspond to effective strain.

See Also: • LS-DYNA Keyword User’s Manual

126 Materials

MAT_GENERAL_VISCOELASTIC A general viscoelastic Maxwell model used for modeling dense continuum rubber and solid explosives.

Field

Comments

Title

Unique name identifying material model

Desc

Optional description of the material model

TITLE_OPTION

If selected material title option is used

MID

Material identification number (Integer > 0)

RO

Mass Density of the material

BULK

Elastic Bulk Modulus

PCF

Tensile Pressure elimination flag (for solid elements only) 1: yes (Tensile Pressure reset to zero) 0: no (Tensile Pressure NOT reset to zero)

EF

Elastic Flag 1: Elastic layer 0: Viscoelastic layer

LCID

Load Curve Id for deviatoric behavior

NT

Number of terms in shear fit

BSTART

Parameter for resetting the exponents in the Relaxation Curve

TRAMP

Optional Time ramp for loading

LCIDK

Load Curve ID defining the bulk behavior

Materials 127 Materials

Field

Comments

NTK

Number of terms in bulk

BSTARTK

Fit Parameter for bulk

TRAMPK

Optional ramp time for bulk loading

NUM_RFS

number of viscoelastic constants

GIi

Optional shear relaxation modulus for the i-th term

BETAIi

Optional shear Decay Constant for the i-th term

KIi

Optional bulk Relaxation Modulus for the i-th term

BETAKIi

Optional bulk Decay Constant for the i-th term

See Also: • LS-DYNA Keyword User’s Manual MAT_HYPERELASTIC_RUBBER A general hyperelastic rubber material model, combined optionally with linear viscoelasticity.

Field

Comments

Title

Unique name identifying material model

Desc

Optional description of the material model

TITLE_OPTION

If selected material title option is used

128 Materials

Field

Comments

MID

Material identification number (Integer > 0)

RO

Mass Density of the material

PR

Poisson’s Ratio

N

Constants to solve for 1: Solve for C10, C01 2: Solve for C10, C01, C11, C20, C02 3: Solve for All constants (C10, C01, C11, C20, C02, and C30)

NV

Number of Prony series terms in fit

G

Shear Modulus

SIGF

Limit stress for frequency independent, frictional, Damping

SGL

Specimen gauge length

SW

Specimen Width

ST

Specimen Thickness

LCID1

Load Curve Id defining Force vs. Actual Change in gauge Length

DATA

Type of experimental data 0:Uniaxial

LCID2

Load Curve Id of relaxation curve

BSTART

Fit Parameter

TRAMP

Optional ramp time for loading

Ci

Material Constants

NUM_RFS

Number of viscoelastic constants

GIi

Optional Shear Relaxation Modulus for the i-th term

BETAIi

Optional Decay Constants for the i-th term

See Also: • LS-DYNA Keyword User’s Manual

Materials 129 Materials

MAT_OGDEN_RUBBER An Ogden rubber material model, combined optionally with linear viscoelasticity.

Field

Comments

Title

Unique name identifying material model

Desc

Optional description of the material model

TITLE_OPTION

If selected material title option is used

MID

Material identification number (Integer > 0)

RO

Mass Density of the material

PR

Poisson’s Ratio

N

Order to fit the Ogden model

NV

Number of Prony series terms in fit

G

Shear Modulus

SIGF

Limit stress for frequency independent, frictional, Damping

SGL

Specimen gauge length

SW

Specimen Width

ST

Specimen Thickness

130 Materials

Field

Comments

LCID1

Load Curve Id defining Force vs. Actual Change in Length

DATA

Type of experimental data 1:Uniaxial 2:Biaxial

LCID2

Load Curve Id of relaxation curve

BSTART

Fit Parameter

TRAMP

Optional ramp time for loading

MUi

i-th Shear Modulus

ALPHAi

i-th Exponent

NUM_RFS

Number of viscoelastic constants

GIi

i-th Optional Shear Relaxation Modulus

BETAIi

i-th Optional Decay Constant

See Also: • LS-DYNA Keyword User’s Manual MAT_SOIL_CONCRETE An efficient soil and concrete material model.

Field

Comments

Title

Unique name identifying material model

Desc

Optional description of the material model

TITLE_OPTION

If selected material title option is used

MID

Material identification number (Integer > 0)

RO

Mass Density of the material

G

Shear Modulus

Materials 131 Materials

Field

Comments

K

Bulk Modulus

LCPV

Load Curve Id defining Pressure vs. Volumetric Strain

LCYP

Load Curve Id defining von Mises Stress vs. Pressure

LCFP

Load Curve Id defining Plastic Strain at which fracture starts vs. Pressure

LCRP

Load Curve Id defining Plastic Strain at which residual strength is released vs. Pressure

PC

Pressure Cutoff

OUT

Output option for plastic strain 0: Volumetric 1: Deviatoric

B

Residual strength factor after cracking

FAIL

Failure flag 0: No 1: Element Erodes when Pressure reached failure pressure 2: No tension in element when Pressure reached failure pressure

See Also: • LS-DYNA Keyword User’s Manual

132 Materials

MAT_HYSTERETIC_SOIL A nested surface material model with five superimposed layers of elasto-perfectly plastic material, each with its own elastic moduli and yield values.

Field

Comments

Title

Unique name identifying material model

Desc

Optional description of the material model

TITLE_OPTION

If selected material title option is used

MID

Material identification number (Integer > 0)

RO

Mass Density of the material

K0

Bulk Modulus

P0

Pressure Cutoff

B

Exponent for pressure sensitive moduli

A0, A1, A2

Yield Function Constants

DF

Damping Factor

RP

Reference Pressure

LCID

Load Curve Id defining Shear Stress vs. Shear Strain

SCLF

Scale Factor o apply on shear stress in LCID

DIL_A

Dilation Parameter A

DIL_B

Dilation Parameter B

DIL_C

Dilation Parameter C

DIL_D

Dilation Parameter D

Materials 133 Materials

Field

Comments

GAMi

Shear Strains (if LCID is zero)

PINIT

Pressure sensitivity flag: .EQ. 0: Use current pressure .EQ. 1: Use pressure from initial stress state .EQ. 2: Use initial “plane stress”pressure .EQ. 3: Use compressive initial vertical stress

TAUi

Shear Stresses (if LCID is zero)

See Also: • LS-DYNA Keyword User’s Manual MAT_RAMBERG_OSGOOD A simple material model of shear behavior, and can be used for seismic analysis.

Field

Comments

Title

Unique name identifying material model

Desc

Optional description of the material model

TITLE_OPTION

If selected material title option is used

MID

Material identification number (Integer > 0)

RO

Mass Density of the material

GAMY

Reference Shear Strain

TAUY

Reference Shear Stress

ALPHA

Stress coefficient

R

Stress exponent

BULK

Elastic Bulk Modulus

134 Materials

See Also: • LS-DYNA Keyword User’s Manual MAT_PLASTICITY_WITH_DAMAGE An elasto-visco-plastic material with an arbitrary stress versus strain curve and arbitrary strain rate dependency. Damage, in this model, is considered before rupture occurs.

Field

Comments

Title

Unique name identifying material model

Desc

Optional description of the material model

TITLE_OPTION

If selected material title option is used

MID

Material identification number (Integer > 0)

RO

Mass Density of the material

E

Young’s Modulus

PR

Poisson’s Ratio

SIGY

Yield Stress

ETAN

Tangent Modulus

EPPF

Plastic Strain, at which material softening begins

TDEL

Minimum time step size for Automatic Element Deletion

C, P

Strain Rate Parameters

LCSS

Load Curve Id defining Effective Stress vs. Effective Plastic Strain

LCSR

Load Curve Id defining Strain Rate Scaling Effect on Yield Stress

EPPFR

Plastic Strain at which material ruptures

VP

Formulation for Rate Effects 0: Scale Yield Stress 1: Viscoplastic Formulation

Materials 135 Materials

Field

Comments

LCDM

Load Curve Id defining nonlinear damage curve

NUMINT

No. of through thickness integration points which must fail before the element is deleted

See Also: • LS-DYNA Keyword User’s Manual MAT_PLASTICITY_WITH DAMAGE_ORTHO_RCDC An elasto-visco-plastic material with an arbitrary stress versus strain curve and arbitrary strain rate dependency. This includes an orthotropic damage model (only for shell elements).

Field

Comments

Title

Unique name identifying material model

Desc

Optional description of the material model

TITLE_OPTION

If selected material title option is used

MID

Material identification number (Integer > 0)

RO

Mass Density of the material

E

Young’s Modulus

PR

Poisson’s Ratio

SIGY

Yield Stress

ETAN

Tangent Modulus

EPPF

Plastic Strain, at which material softening begins

TDEL

Minimum time step size for Automatic Element Deletion

136 Materials

Field

Comments

C, P

Strain Rate Parameter

LCSS

Load Curve Id defining Effective Stress vs. Effective Plastic Strain

LCSR

Load Curve Id defining Strain Rate Scaling Effect on Yield Stress

EPPFR

Plastic Strain at which material ruptures

VP

Formulation for Rate Effects 0: Scale Yield Stress 1: Viscoplastic Formulation

NUMINT

No. of through thickness integration points which must fail before the element is deleted

LCDM

Load Curve Id defining nonlinear damage curve

ALPHA

Parameter α

BETA

Parameter β

GAMMA

Parameter γ

D0

Parameter D0

B

Parameter b

LAMDA

Parameter λ

DS

Parameter Ds

L

Optional characteristic element length for this material.

See Also: • LS-DYNA Keyword User’s Manual

Materials 137 Materials

MAT_FU_CHANG_FOAM A material such as low and medium density foams, for hysteric unloading behaviors. Rate effects can be included in this material model.

Field

Comments

Title

Unique name identifying material model

Desc

Optional description of the material model

TITLE_OPTION

If selected material title option is used

MID

Material identification number (Integer > 0)

RO

Mass Density of the material

E

Young’s Modulus

ED

Young’s Relaxation Modulus for rate effect

TC

Tension Cutoff Stress

FAIL

Failure option after Cutoff Stress is reached 0: Tensile Stress Remains at cutoff 1: Tensile Stress Resets to Zero

DAMP

Viscous Coefficient

TBID

Table Id for nominal Stress vs. Strain

138 Materials

Field BVFLAG

Comments Bulk Viscosity activation Flag 0: No 1: Active

SFLAG

Strain Rate Flag 0: True strain 1: Engineering strain

RFLAG

Strain Rate evaluation flag 0 : First principal direction 1 : Principal strain rates for each principal direction 2: Volumetric strain rate

TFLAG

Tensile Stress Evaluation Flag 0: Linear 1: Input via Load Curves with the tensile response corresponding to negative values of stress and strain

PVID

Load Curve Id defining Pressure vs. Volumetric Strain

SRAF

Strain Rate averaging flag 0: Weighted running average 1: Average of the last twelve values

REF

User reference geometry to initialize the stress tensor.: .EQ. 0: OFF .EQ. 1: ON

HU

Hysteric unloading factor between 0 and 1 (default = 1, i.e. no energy dissipation).

D0, N0, C0, Ni, Ci

Material Constants

AIJ, SIJ

Material Constants

MINR

Minimum strain rate of interest

MAXR

Maximum strain rate of interest

SHAPE

Shape factor for unloading. Active for nonzero values of the hysteric unloading factor HU.

Materials 139 Materials

See Also: • LS-DYNA Keyword User’s Manual MAT_WINFRITH_CONCRETE A smeared crack, smeared rebar, material model (only for the 8-noded single integration point continuum element).

Field

Comments

Title

Unique name identifying material model

Desc

Optional description of the material model

TITLE_OPTION

If selected material title option is used

MID

Material identification number (Integer > 0)

RO

Mass Density of the material

TM

Tangent Modulus of Concrete

PR

Poisson’s Ratio

UCS

Uniaxial Compression Strength

UTS

Uniaxial Tensile Strength

FE

Depends on value for RATE If RATE = 0, FE is Fracture Energy per unit area in opening crack If RATE = 1, FE is crack width at which crack-normal tensile stress becomes zero

ASIZE

Aggregate size (radius)

E

Young’s Modulus for rebar

YS

Yield Stress for rebar

140 Materials

Field

Comments

EH

Hardening Modulus for rebar

UELONG

Ultimate elongation before rebar fails

RATE

Rate effects Flag 0: Included (MAT_0 84) 1: Turned off (MAT_0 85)

CONM

Factor to convert model mass units to kg

CONL

Factor to convert model length units to meters (if CONM .GT. 0)

CONT

Factor to convert model time units to seconds

LCID

Defining Pressure vs. Volumetric Strain

See Also: • LS-DYNA Keyword User’s Manual

Materials 141 Materials

MAT_WINFRITH_CONCRETE_REINFORCEMENT A rebar reinforcement material model (material type 84). Reinforcement quantity is defined as the ratio of the cross-sectional area of steel, relative to the cross-sectioanl area of concrete in the element (or layer).

Field

Comments

Title

Unique name identifying material model

Desc

Optional description of the material model

TITLE_OPTION

If selected material title option is used

MID

Material identification number (Integer > 0)

RO

Mass Density of the material

TM

Tangent Modulus of Concrete

PR

Poisson’s Ratio

UCS

Uniaxial Compression Strength

UTS

Uniaxial Tensile Strength

FE

Depends on value for RATE If RATE = 0, FE is Fracture Energy per unit area in opening crack If RATE = 1, FE is crack width at which crack-normal tensile stress becomes zero

142 Materials

Field

Comments

ASIZE

Aggregate size (radius)

E

Young’s Modulus for rebar

YS

Yield Stress for rebar

EH

Hardening Modulus for rebar

UELONG

Ultimate elongation before rebar fails

RATE

Rate effects Flag 0: Included (MAT_0 84) 1: Turned off (MAT_0 85)

CONM

Factor to convert model mass units to kg

CONL

Factor to convert model length units to meters (if CONM .GT. 0)

CONT

Factor to convert model time units to seconds

LCID

Defining Pressure vs. Volumetric Strain

EID1

First element Id in group

EID2

Last element Id in group

INC

Element increment for genaration

XR

X-reinforcement quantity (for bars running parallel to global x-axis)

YR

Y-reinforcement quantity (for bars running parallel to global y-axis)

ZR

Z-reinforcement quantity (for bars running parallel to global z-axis)

PID

Part Id of reinforced elements

AXIS

Axis normal to layer: .EQ. 1: A and B are parallel to global Y and Z, respectively .EQ. 2 A and B are parallel to global X and Z, respectively .EQ. 3: A and B are parallel to global X and Y, respectively

COOR

Coordinate location of layer (X-coordinate if AXIS = 1, Y-Coordinate if AXIS = 2, Z-Coordinate if AXIS = 3)

RQA

Reinforcement quantity (A)

RQB

Reinforcement quantity (B)

Materials 143 Materials

See Also: • LS-DYNA Keyword User’s Manual MAT_ORTHOTROPIC_VISCOELASTIC A viscoelastic material model (only for shell elements).

Field

Comments

Title

Unique name identifying material model

Desc

Optional description of the material model

TITLE_OPTION

If selected material title option is used

MID

Material identification number (Integer > 0)

RO

Mass Density of the material

EA

Young’s Modulus in Longitudinal Direction

EB

Young’s Modulus in Transverse Direction

EC

Young’s Modulus in Normal Direction

VF

Volume fraction for viscoelastic material

K

Elastic Bulk Modulus

G0

Short time Shear Modulus

GINF

Long time Shear Modulus

BETA

Decay Constant

144 Materials

Field

Comments

PRBA, PRCA, PRCB

Poisson’s Ratio in the ba, ca and cb directions

GAB, GBC, GCA

Shear Moduli in the ab, bc and ca directions

AOPT

Material Axes option 0: Locally orthotropic with material axes determined by element nodes 1, 2, and 4. (Node 1 is the local origin, Node 2 is along the local a- axis; Local c-axis is the cross product of local a-axis, and the vector from node 1 to node 4; Local b- axis is the cross product of loca c- and a- axes.) 1: Locally orthotropic with material axis determined by a point in space, and the global location of the element center; this is the a- direction. This option is for solid elements only. 2: Globally orthotropic with material axis determined by3 vectors below. 3: Locally orthotropic with material axis determined by rotating the material axes about the element normal by an angle, BETA, from a line in the plane of the element defined by the cross product of the vector v with the element normal.

MANGLE

Material Angle (Degrees), for AOPT=3

blank1, blank2, blank3

Blank Fields

Ai

Component of Vector a, for AOPT=2

Vi

Component of Vector v, for AOPT=3

Di

Component of Vector d, for AOPT=2

See Also: • LS-DYNA Keyword User’s Manual

Materials 145 Materials

MAT_CELLULAR_RUBBER A material model for a cellular rubber with confined air pressure, combined with linear viscoelasticity.

Field

Comments

Title

Unique name identifying material model

Desc

Optional description of the material model

TITLE_OPTION

If selected material title option is used

MID

Material identification number (Integer > 0)

RO

Mass Density of the material

PR

Poisson’s Ratio

N

Order or fit

SGL

Specimen Gauge Length

SW

Specimen Width

ST

Specimen Thickness

LCID

Load Curve Id defining the Force vs. Actual Change in gauge Length

C10, C01, C11, C20, C02

Material Constants

P0

Initial Air Pressure

PHI

Ratio of cellular rubber to rubber density

IVS

Initial Volumetric Strain

G

Optional shear relaxation modulus, G, for rate effects

BETA

Optional Decay Constant

146 Materials

See Also: • LS-DYNA Keyword User’s Manual MAT_MTS This MTS material model, developed by Maudlin, Davidson, and Henninger [1990], is used for applications involving high pressures, large strains, and high strain rates. This model uses dislocation mechanics and provides an understanding of the plastic deformation process in ductile materials.

Field

Comments

Title

Unique name identifying material model

Desc

Optional description of the material model

TITLE_OPTION

If selected material title option is used

MID

Material identification number (Integer > 0)

RO

Mass Density of the material

SIGA

Dislocation interaction with long-range barriers

SIGI

Dislocation interaction with interstitial atoms

SIGS

Dislocation interaction with solute atoms

SIG0

NOT used

BULK

Bulk Modulus (for shell elements)

HF0, HF1, HF2

Dislocation generation material constants

SIGSO

Saturation Threshold stress at 0 degrees K

Materials 147 Materials

Field

Comments

EDOTSO, EDOTO, EDOTI, EDOTS

Reference Strain rates

BURG

Magnitude of Burgers vector

CAPA

Material Constant, A

BOLTZ

Boltzmann’s constant, k

SM0, SM1, SM2

Shear Modulus Constants

G0, GOI, GOS

Normalized activation energies

PINV, QINV, PINVI, QINVI, PINVS., QINVS., ALPHA

Material Constants

RHOCPR

Product of density and specific heat

TEMPRF

Initial Element Temperature

EPSO

Factor to normalize strain rate

See Also: • LS-DYNA Keyword User’s Manual MAT_PLASTICITY_POLYMER An elasto-plastic material model with arbitrary stress versus strain curve, and arbitrary strain rate dependency.

Field

Comments

Title

Unique name identifying material model

Desc

Optional description of the material model

TITLE_OPTION

If selected material title option is used

148 Materials

Field

Comments

MID

Material identification number (Integer > 0)

RO

Mass Density of the material

PR

Poisson’s Ratio

C, P

Strain Rate Parameters

LCSS

Load Curve Id defining Effective Stress vs. Total Effective Strain

LCSR

Load Curve Id defining Strain Rate Scaling effect on Yield Stress

EFTX

Failure Flag 0: Failure determined by Maximum tensile strain 1: Failure determined only by tensile strain in local x direction 2: Failure determined only by tensile strain in local y direction

DAMP

Stiffness proportional damping ratio

RATEFAC

Filtering factor for strain rate effect

LCFAIL

Load Curve Id defining variation of Failure strain with Strain rate

See Also: • LS-DYNA Keyword User’s Manual MAT_ACOUSTIC Defines the properties of materials used to track low pressure waves in acoustic media, like air or water (only for acoustic pressure elements).

Field

Comments

Title

Unique name identifying material model

Desc

Optional description of the material model

TITLE_OPTION

If selected material title option is used

Materials 149 Materials

Field

Comments

MID

Material identification number (Integer > 0)

RO

Mass Density of the material

C

Sound Speed

BETA

Damping Factor

CF

Cavitation Flag 0: Off 1: On

ATMOS

Atmospheric Pressure

GRAV

Gravitational Acceleration constant

XP, YP, ZP

Coordinates of free surface point

XN, YN, ZN

Direction cosines of free surface normal vector

See Also: • LS-DYNA Keyword User’s Manual

150 Materials

MAT_SOFT_TISSUE Defines a transversely isotropic hyperelastic material that represents biological soft tissue such as ligaments, tendons, and fascia.

Field

Comments

Title

Unique name identifying material model

Desc

Optional description of the material model

TITLE_OPTION

If selected material title option is used

MID

Material identification number (Integer > 0)

RO

Mass Density of the material

Ci

Hyperelastic Coefficients

XK

Bulk Modulus

XLAM

Stretch ratio at which fibers are straightened

FANG

Fiber angle in local shell coordinate system (shell elements only)

XLAMO

Initial fiber stretch

FAILSF

stretch ratio for ligament fibers at failure (shell elements only). If zero, failure is not considered.

FAILSM

stretch ratio for surrounding matrix material at failure (shell elements only). If zero, failure is not considered.

Materials 151 Materials

Field

Comments

FAILSHR

Shear strain at failure of a material point (shell elements only). If zero, failure is not considered. This failure value is independent of FAILSF and FAILSM.

AOPT

0: Locally orthotropic with material axes determined by element nodes 1, 2, and 4. (Node 1 is the local origin, Node 2 is along the local a- axis; Local c-axis is the cross product of local a-axis, and the vector from node 1 to node 4; Local b- axis is the cross product of loca c- and a- axes.) 1: Locally orthotropic with material axis determined by a point in space, and the global location of the element center; this is the a- direction. This option is for solid elements only. 2: Globally orthotropic with material axis determined by3 vectors below.

AX, AY, AZ

Components of first material axis point/vector

BX, BY, BZ

Components of second material axis point/vector

LAX, LAY, LAZ

Component of fiber orientation vector (Brick elements only)

MACF

Material axes change flag for brick element: =1 No Change; = 2 switch mateial axes a and b =3 switch material axes a and c ; =4 switch material axes b and c

See Also: • LS-DYNA Keyword User’s Manual

152 Materials

MAT_SOFT_TISSUE_VISCO A transversely isotropic hyperelastic material model that represents biological soft tissue such as ligaments, tendons, and fascia. This model has a viscoelastic option activating a six-term Prony series kernel for the relaxation function.

Field

Comments

Title

Unique name identifying material model

Desc

Optional description of the material model

TITLE_OPTION

If selected material title option is used

MID

Material identification number (Integer > 0)

RO

Mass Density of the material

Ci

Hyperelastic Coefficients

XK

Bulk Modulus

XLAM

Stretch ratio at which fibers are straightened

FANG

Fiber angle in local shell coordinate system (shell elements only)

XLAMO

Initial fiber stretch

Materials 153 Materials

Field AOPT

Comments 0: Locally orthotropic with material axes determined by element nodes 1, 2, and 4. (Node 1 is the local origin, Node 2 is along the local a- axis; Local c-axis is the cross product of local a-axis, and the vector from node 1 to node 4; Local b- axis is the cross product of loca c- and a- axes.) 1: Locally orthotropic with material axis determined by a point in space, and the global location of the element center; this is the a- direction. This option is for solid elements only. 2: Globally orthotropic with material axis determined by3 vectors below.

AX, AY, AZ

Components of first material axis point/vector

BX, BY, BZ

Components of second material axis point/vector

LAX, LAY, LAZ

Component of fiber orientation vector (Brick elements only)

Si

Spectral strengths for prony series relaxation kernel

Ti

Characteristic time for prony series relaxation kernel

See Also: • LS-DYNA Keyword User’s Manual MAT_ELASTIC_6DOF_SPRING_DISCRETE_BEAM A material model for simulating the effects of nonlinear elastic and nonlinear viscous beams using six springs each acting along one of it six degrees-of-freedom.

Field

Comments

Title

Unique name identifying material model

Desc

Optional description of the material model

TITLE_OPTION

If selected material title option is used

MID

Material identification number (Integer > 0)

RO

Mass Density of the material

TPIDR

Part Id governing the Translational motion in the local r direction (If zero, no force is computed in this direction)

154 Materials

Field

Comments

TPIDS

Part Id governing the Translational motion in the local s direction (If zero, no force is computed in this direction)

TPIDT

Part Id governing the Translational motion in the local t direction (If zero, no force is computed in this direction)

RPIDR

Part Id governing the Rotational motion about the local r direction (If zero, no moment is computed in this direction)

RPIDS

Part Id governing the Rotational motion about the local s direction (If zero, no moment is computed in this direction)

RPIDT

Part Id governing the Rotational motion about the local t direction (If zero, no moment is computed in this direction)

See Also: • LS-DYNA Keyword User’s Manual MAT_INELASTIC_SPRING_DISCRETE_BEAM A material model for elastoplastic springs, with damping to be represented with discrete beam elements. A yield force versus deflection is used which can vary in tension and compression.

Field

Comments

Title

Unique name identifying material model

Desc

Optional description of the material model

TITLE_OPTION

If selected material title option is used

MID

Material identification number (Integer > 0)

RO

Mass Density of the material

K

Elastic Loading/Unloading Stiffness

F0

Optional initial force

D

Optional viscous damping coefficient

Materials 155 Materials

Field

Comments

CDF

Compressive displacement at failure

TDF

Tensile Displacement at failure

FLCID

Load Curve Id defining Yield Force vs. Plastic Displacement

HLCID

Load Curve Id defining Force vs. Relative Velocity

C1, C2

Damping Coefficients

DLE

Scale Factor for time unit

GLCID

Load Curve Id defining a Scale Factor vs. Deflection for Load Curve Id, HLCID

See Also: • LS-DYNA Keyword User’s Manual MAT_INELASTIC_6DOF_SPRING_DISCRETE_BEAM A material model for nonlinear inelastic and nonlinear viscous beams using six springs each acting along one of it six degrees-of-freedom.

Field

Comments

Title

Unique name identifying material model

Desc

Optional description of the material model

TITLE_OPTION

If selected material title option is used

MID

Material identification number (Integer > 0)

RO

Mass Density of the material

TPIDR

Part Id governing the Translational motion in the local r direction (If zero, no force is computed in this direction)

TPIDS

Part Id governing the Translational motion in the local s direction (If zero, no force is computed in this direction)

TPIDT

Part Id governing the Translational motion in the local t direction (If zero, no force is computed in this direction)

156 Materials

Field

Comments

RPIDR

Part Id governing the Rotational motion about the local r direction (If zero, no moment is computed in this direction)

RPIDS

Part Id governing the Rotational motion about the local s direction (If zero, no moment is computed in this direction)

RPIDT

Part Id governing the Rotational motion about the local t direction (If zero, no moment is computed in this direction)

See Also: • LS-DYNA Keyword User’s Manual MAT_BRITTLE_DAMAGE A material model with anisotropic brittle damage characteristics, used mainly for concrete but can be applied for a variety of brittle materials.

Field

Comments

Title

Unique name identifying material model

Desc

Optional description of the material model

TITLE_OPTION

If selected material title option is used

MID

Material identification number (Integer > 0)

RO

Mass Density of the material

E

Young’s Modulus

PR

Poisson’s Ratio

TLIMIT

Tensile Limit

SLIMIT

Shear Limit

FTOUGH

Fracture Toughness

SRETEN

Shear Retention

VISC

Viscosity

Materials 157 Materials

Field

Comments

FRA_RF

Fraction of reinforcement in section

E_RF

Young’s Modulus of Reinforcement

YS_RF

Yield Stress of Reinforcement

EH_RF

Hardening Modulus of Reinforcement

FS_RF

Failure Strain of Reinforcement

SIGY

Compressive Yield Stress

See Also: • LS-DYNA Keyword User’s Manual MAT_GENERAL_JOINT_DISCRETE_BEAM Defines the properties of a general joint constraining any combination of degrees of freedom between two nodes.

Field

Comments

Title

Unique name identifying material model

Desc

Optional description of the material model

TITLE_OPTION

If selected material title option is used

MID

Material identification number (Integer > 0)

RO

Mass Density of the material

TR

Translational Constraint Code along r-axis 0: Free 1:Fixed

158 Materials

Field TS

Comments Translational Constraint Code along s-axis 0: Free 1:Fixed

TT

Translational Constraint Code along t-axis 0: Free 1:Fixed

RR

Rotational Constraint Code about r-axis 0: Free 1:Fixed

RS

Rotational Constraint Code about s-axis 0: Free 1:Fixed

RT

Rotational Constraint Code about t-axis 0: Free 1:Fixed

RPST

Penalty stiffness scale factor for translational constraints

RPSR

Penalty stiffness scale factor for rotational constraints

See Also: • LS-DYNA Keyword User’s Manual

Materials 159 Materials

MAT_SIMPLIFIED_JOHNSON_COOK A material model used for problems where the strain rates vary over a large range. In this model, thermal effect and damage are ignored and maximum stress is directly limited since thermal softening is not available.

Field

Comments

Title

Unique name identifying material model

Desc

Optional description of the material model

TITLE_OPTION

If selected material title option is used

MID

Material identification number (Integer > 0)

RO

Mass Density of the material

E

Young’s Modulus

PR

Poisson’s Ratio

VP

Formulation for Rate Effects 0: Scale Yield Stress 1: Viscoplastic Formulation

A, B, N, C

Parameters used in the Johnson-Cook flow stress equation

PSFAIL

Effective Plastic Strain at Failure

SIGMAX

Maximum Stress obtained from Work Hardening before rate effects are added

SIGSAT

Saturation Stress

EPSO

Effective Plastic Strain rate

See Also: • LS-DYNA Keyword User’s Manual

160 Materials

MAT_SIMPLIFIED_JOHNSON_COOK_ORTHO_DAMAGE Defines the properties of a material used for problems where the strain rates vary over a large range. Orthotropic damage is included as a means for treating failure in aluminum panels (only for shell elements with multiple through thickness integration points).

Field

Comments

Title

Unique name identifying material model

Desc

Optional description of the material model

TITLE_OPTION

If selected material title option is used

MID

Material identification number (Integer > 0)

RO

Mass Density of the material

E

Young’s Modulus

PR

Poisson’s Ratio

VP

Formulation for Rate Effects 0: Scale Yield Stress 1: Viscoplastic Formulation

EPPFR

Plastic Strain at which the material ruptures

LCDM

Load Curve Id defining nonlinear damage curve

NUMINT

No. of through thickness integration points which must fail before element is deleted

A, B, N, C

Parameters used in the Johnson-Cook flow stress equation

PSFAIL

Effective Plastic Strain at Failure

SIGMAX

Maximum Stress obtained from Work Hardening before rate effects are added

SIGSAT

Saturation Stress

EPSO

Effective Plastic Strain rate

Materials 161 Materials

See Also: • LS-DYNA Keyword User’s Manual MAT_SPOTWELD A material model for spotweld modeled with beam element type 9, and solid element type 1.

Field

Comments

Title

Unique name identifying material model

Desc

Optional description of the material model

TITLE_OPTION

If selected material title option is used

MID

Material identification number (Integer > 0)

RO

Mass Density of the material

E

Young’s Modulus

PR

Poisson’s Ratio

SIGY

Initial Yield Stress

ET

Hardening Modulus

DT

Time Step Size for Mass Scaling

TFAIL

Failure Time (Ignored if value is zero)

EFAIL

Effective Plastic Strain at Failure

NRR

Axial force resultant NrrF (or Maximum Axial Stress σrrF) at failure

NRS

Force resultant NrsF (or Maximum Shear Stress τF) at failure

NRT

Force resultant NrtF at failure

MRR

Torsional moment resultant MrrF at failure

MSS

Moment resultant MssF at failure

MTT

Moment resultant MttF at failure

NF

No. of force vectors stored for filtering

162 Materials

See Also: • LS-DYNA Keyword User’s Manual MAT_SPOTWELD_DAMAGE-FAILURE A material model used in spotweld, modeled with beam element type 9, and solid element type 1. Damage parameters are also included in this model.

Field

Comments

Title

Unique name identifying material model

Desc

Optional description of the material model

TITLE_OPTION

If selected material title option is used

MID

Material identification number (Integer > 0)

RO

Mass Density of the material

E

Young’s Modulus

PR

Poisson’s Ratio

SIGY

Initial Yield Stress

ET

Hardening Modulus

DT

Time Step Size for Mass Scaling

TFAIL

Failure Time (Ignored if value is zero)

EFAIL

Effective Plastic Strain at Failure

NRR

Axial force resultant NrrF (or Maximum Axial Stress σrrF) at failure

NRS

Force resultant NrsF (or Maximum Shear Stress τF) at failure

NRT

Force resultant NrtF at failure

MRR

Torsional moment resultant MrrF at failure

Materials 163 Materials

Field

Comments

MSS

Moment resultant MssF at failure

MTT

Moment resultant MttF at failure

NF

No. of force vectors stored for filtering

RS

Rupture Strain

OPT

Failure Option 0: Resultant based failure 1: Stress based failure computed from resultant (Toyota) 2: User subroutine to determine failure 3: Notch stress based failure (beam weld only) 4: Stress intensity factor at failure (beam weld only) 5: Structural stress at failure (beam weld only)

FVAL

Failure parameter: .EQ. 3: Notch stress value at failure (σKF) .EQ. 4: Stress intensity factor value at failure (KeqF) .EQ. 5: Structural stress value at failure (σSF) .EQ. 6: Number of cycles that that failure condition must be met to trigger beam deletion. .EQ. 9: Number of cycles that that failure condition must be met to trigger beam deletion. Note: Values of -2, -1, 0, 1, 2, 7 - Not used

TRUE_T

True weld thickness. This optional value is available for solid element failure by OPT = 0, 1, 7, or -2.

BETA

Damage model decay rate.

See Also: • LS-DYNA Keyword User’s Manual MAT_SPOTWELD_DAIMLERCHRYSLER A material model used in spotweld, modeled with solid element type 1, with type 6 hour glass control. Special Damage parameters are used in this model.

164 Materials

Field

Comments

Title

Unique name identifying material model

Desc

Optional description of the material model

TITLE_OPTION

If selected material title option is used

MID

Material identification number (Integer > 0)

RO

Mass Density of the material

E

Young’s Modulus

PR

Poisson’s Ratio

DT

Time Step Size for Mass Scaling

TFAIL

Failure Time (Ignored if value is zero)

EFAIL

Effective Plastic Strain at Failure

NF

Number of failure function evaluations stored for filtering by time averaging.

RS

Rupture Strain

TRUE_T

True weld thickness for hexahedron solid weld element.

CON_ID

Connection Id of *DEFINE_CONNECTION

See Also: • LS-DYNA Keyword User’s Manual

Materials 165 Materials

MAT_GEPLASTIC_SRATE_2000a Defines properties for the General Electric’s commercially available thermoplastics subjected to high strain rates. This model features variation of yield stress dependent upon strain rate, cavitation effects of rubber modified material, and automatic element deletion for either ductile or brittle materials.

Field

Comments

Title

Unique name identifying material model

Desc

Optional description of the material model

TITLE_OPTION

If selected material title option is used

MID

Material identification number (Integer > 0)

RO

Mass Density of the material

E

Young’s Modulus

PR

Poisson’s Ratio

RATESF

Constant in plastic strain rate equation

EDOTO

Reference Strain Rate

ALPHA

Pressure Sensitive Factor

LCSS

Load Curve Id (or Table Id) for post Yield Stress behavior vs. Strain

LCFEPS

Load Curve Id for Plastic failure Strain vs. Strain Rate

LCFSIG

Load Curve Id for Maximum principal failure Stress vs. Strain Rate

LCE

Load Curve Id for Unloading Moduli vs. Plastic Strain

See Also: • LS-DYNA Keyword User’s Manual

166 Materials

MAT_HYPERBOLIC_SIN Defines properties for modeling materials with temperature and rate dependent plasticity.

Field

Comments

Title

Unique name identifying material model

Desc

Optional description of the material model

TITLE_OPTION

If selected material title option is used

MID

Material identification number (Integer > 0)

RO

Mass Density of the material

E

Young’s Modulus

PR

Poisson’s Ratio

T

Initial Temperature

HC

Heat Generation Coefficient

VP

Formulation for Rate Effects 0: Scale Yield Stress 1: Viscoplastic Formulation

ALPHA, N, A, Q, G

Material constitutive constants

EPSO

Effective plastic strain rate

See Also: • LS-DYNA Keyword User’s Manual

Materials 167 Materials

MAT_ANISOTROPIC_VISCOPLASTIC Defines an anisotropic viscoplastic material that is applied to either shell or brick elements. The material constants may be input directly, or by stress-strain data. If stress-strain data is provided, a least squares fit will be performed to determine the constants.

Field

Comments

Title

Unique name identifying material model

Desc

Optional description of the material model

TITLE_OPTION

If selected material title option is used

MID

Material identification number (Integer > 0)

RO

Mass Density of the material

E

Young’s Modulus

PR

Poisson’s Ratio

SIGY

Initial Yield Stress

FLAG

Flag for material parameters

LCSS

Load Curve Id for Effective Stress vs. Effective Plastic Strain

168 Materials

Field ALPHA

Comments α distribution hardening: =0: Kinematic hardening = 1: Isotropic hardening

QRi, CRi

Isotropic Hardening Parameters

QXi, CXi

Kinematic Hardening Parameters

VK, VM

Viscous Material Parameters

R00/F

R00 for shell, or F for solid

R45/G

R45 for shell, or G for solid

R90/H

R90 for shell, or H for solid

L, M, N

Parameters (for solid elements only

AOPT

Material Axes option 0: Locally orthotropic with material axes determined by element nodes 1, 2, and 4. (Node 1 is the local origin, Node 2 is along the local a- axis; Local c-axis is the cross product of local a-axis, and the vector from node 1 to node 4; Local b- axis is the cross product of loca c- and a- axes.) 1: Locally orthotropic with material axis determined by a point in space, and the global location of the element center; this is the a- direction. This option is for solid elements only. 2: Globally orthotropic with material axis determined by3 vectors below. 3: Locally orthotropic with material axis determined by rotating the material axes about the element normal by an angle, BETA, from a line in the plane of the element defined by the cross product of the vector v with the element normal. 4: Locally orthotropic in cylindrical coordinate system with the material axis determined by a vector v, and an originating point, P, which defines the centerline axis. This option is for solid elements only.

FAIL

Failure flag: .LT. 0: user defined failure subroutine to determine failure. .EQ. 0: failure is not considered .GT. 0: Plastic strain to failure. When the plastic strain reaches this value, the element is deleted from calculation.

Materials 169 Materials

Field

Comments

NUMINT

Number of integration point which must fail before element is deleted.. If zero, all points must fail. This option applies to shell elements only.

MACF

Material axes change flag: =1 No Change; = 2 switch mateial axes a and b =3 switch material axes a and c ; =4 switch material axes b and c

XP, YP, ZPP

Coordinates of point p, for AOPT=1

Ai

Component of Vector a, for AOPT=2

Vi

Component of Vector v, for AOPT=3

Di

Component of Vector d, for AOPT=2

BETA

Material Angle (Degrees), for AOPT=3

See Also: • LS-DYNA Keyword User’s Manual

170 Materials

MAT_ANISOTROPIC_PLASTIC This anisotropic plastic material model is a simplified version of the MAT_ANISOTROPIC_VISCOPLASTIC model. This model applies to shell elements only.

Field

Comments

Title

Unique name identifying material model

Desc

Optional description of the material model

TITLE_OPTION

If selected material title option is used

MID

Material identification number (Integer > 0)

RO

Mass Density of the material

E

Young’s Modulus

PR

Poisson’s Ratio

SIGY

Initial Yield Stress

LCSS

Load Curve Id for effective Stress vs. effective plastic Strain

QRi, CRi

Isotropic Hardening Parameters

QXi, CXi

Kinematic Hardening Parameters

R00/F

R00 for shell or F for solid

R45/G

R45 for shell or G for solid

R90/H

R90 for shell or H for solid

Materials 171 Materials

Field

Comments

S11, S22, S33, S12

Yield Stress in the x, y, z and xy direction, respectively

AOPT

Material Axes option 0: Locally orthotropic with material axes determined by element nodes 1, 2, and 4. (Node 1 is the local origin, Node 2 is along the local a- axis; Local c-axis is the cross product of local a-axis, and the vector from node 1 to node 4; Local b- axis is the cross product of loca c- and a- axes.) 1: Locally orthotropic with material axis determined by a point in space, and the global location of the element center; this is the a- direction. This option is for solid elements only. 2: Globally orthotropic with material axis determined by3 vectors below. 3: Locally orthotropic with material axis determined by rotating the material axes about the element normal by an angle, BETA, from a line in the plane of the element defined by the cross product of the vector v with the element normal. 4: Locally orthotropic in cylindrical coordinate system with the material axis determined by a vector v, and an originating point, P, which defines the centerline axis. This option is for solid elements only.

XP, YP, ZP

Coordinates of point p, for AOPT=1

Ai

Components of Vector a, for AOPT=2

Vi

Components of Vector v, for AOPT=3

Di

Components of Vector d, for AOPT=2

BETA

Material Angle (Degrees), for AOPT=3

See Also: • LS-DYNA Keyword User’s Manual

172 Materials

MAT_DAMAGE_1 Defines properties for a continuum damage mechanics material model which includes anisotropy and viscoplasticity. This model is applied to shell, thick shell and brick elements.

Field

Comments

Title

Unique name identifying material model

Desc

Optional description of the material model

TITLE_OPTION

If selected material title option is used

MID

Material identification number (Integer > 0)

RO

Mass Density of the material

E

Young’s Modulus

PR

Poisson’s Ratio

SIGY

Initial Yield Stress

LCSS

Load Curve Id for effective Stress vs. effective plastic Strain

LCDM

Load Curve Id defining nonlinear damage (for FLAG = -1)

Qi, Ci

Isotropic Hardening Parameters

EPSD

Damage Threshold, rd

Materials 173 Materials

Field

Comments

S

Damage Material Constant

EPSR

Plastic strain at which material ruptures

DC

Critical Damage valueDc

FLAG

Flag for Localization -1: Anisotropic damage 0: No calculation of localization due to damage 1: Flag those elements where local stabilization occurs

VK, VM

Viscous Material Parameter

R00/F

R00 for shell or F for solid

R45/G

R45 for shell or G for solid

R90/H

R90 for shell or H for solid

L, M, N

Parameters (for solid elements only

AOPT

Material Axes option 0: Locally orthotropic with material axes determined by element nodes 1, 2, and 4. (Node 1 is the local origin, Node 2 is along the local a- axis; Local c-axis is the cross product of local a-axis, and the vector from node 1 to node 4; Local b- axis is the cross product of loca c- and a- axes.) 1: Locally orthotropic with material axis determined by a point in space, and the global location of the element center; this is the a- direction. This option is for solid elements only. 2: Globally orthotropic with material axis determined by3 vectors below. 3: Locally orthotropic with material axis determined by rotating the material axes about the element normal by an angle, BETA, from a line in the plane of the element defined by the cross product of the vector v with the element normal. 4: Locally orthotropic in cylindrical coordinate system with the material axis determined by a vector v, and an originating point, P, which defines the centerline axis. This option is for solid elements only.

XP, YP, ZP

Coordinates of point p, for AOPT=1

Ai

Component of Vector a, for AOPT=2

Vi

Component of Vector v, for AOPT=3

174 Materials

Field

Comments

Di

Component of Vector d, for AOPT=2

BETA

Material Angle (Degrees), for AOPT=3

See Also: • LS-DYNA Keyword User’s Manual MAT_DAMAGE_2 Defines properties for an elastic viscoplastic material model combined with the continuum damage mechanics. This model is applied to shell, thick shell and brick elements.

Field

Comments

Title

Unique name identifying material model

Desc

Optional description of the material model

TITLE_OPTION

If selected material title option is used

MID

Material identification number (Integer > 0)

RO

Mass Density of the material

E

Young’s Modulus

PR

Poisson’s Ratio

SIGY

Yield Stress

ETAN

Tangent Modulus

FAIL

Failure flag =0: Failure due to plastic strain not considered > 0: Plastic strain to failure considered. When the plastic strain reaches this value, the element is deleted from calculation.

Materials 175 Materials

Field

Comments

TDEL

Minimum time step for Automatic Element Deletion

C, P

Strain Rate Parameters

LCSS

Load Curve Id defining effective Stress vs. effective plastic Strain

LCSR

Load Curve Id defining Strain Rate Scaling Effect on Yield Stress

EPSD

Damage Threshold, rd

S

Damage Material Constant

DC

Critical Damage valueDc

See Also: • LS-DYNA Keyword User’s Manual MAT_ELASTIC_VISCOPLASTIC_THERMAL Defines properties for an elastic viscoplastic material with thermal effects.

Field

Comments

Title

Unique name identifying material model

Desc

Optional description of the material model

TITLE_OPTION

If selected material title option is used

MID

Material identification number (Integer > 0)

RO

Mass Density of the material

E

Young’s Modulus

PR

Poisson’s Ratio

176 Materials

Field

Comments

SIGY

Initial Yield Stress

ALPHA

Coefficient of thermal expansion

LCSS

Load Curve Id for effective Stress vs. effective plastic Strain

QRi, CRi

Isotropic Hardening Parameters

QXi, CXi

Kinematic Hardening Parameters

C, P

Viscous Material Parameters

LCE

Load Curve Id defining Young’s Modulus vs. Temperature

LCPR

Load Curve Id defining Poisson’s Ratio vs. Temperature

LCSIGY

Load Curve Id defining Initial Yield Stress vs. Temperature

LCR

Load Curve Id defining for Parameters QR1 and QR2 vs. Temperature

LCX

Load Curve Id defining for Parameters QX1 and QX2 vs. Temperature

LCALPH

Load Curve Id defining Coefficient of thermal expansion vs. Temperature

LCC

Load Curve Id defining scaling Viscous material parameter C vs. Temperature

LCP

Load Curve Id defining scaling Viscous material parameter P vs. Temperature

See Also: • LS-DYNA Keyword User’s Manual

Materials 177 Materials

MAT_JOHNSON_HOLMQUIST_CERAMICS Defines properties for a material used to model ceramics, glass and other brittle materials.

Field

Comments

Title

Unique name identifying material model

Desc

Optional description of the material model

TITLE_OPTION

If selected material title option is used

MID

Material identification number (Integer > 0)

RO

Mass Density of the material

G

Shear Modulus

A

Intact normalized strength parameter

B

Fractured normalized strength parameter

C

Strength Parameter (for strain rate dependence)

M

Fracture strength parameter (Pressure exponent)

N

Intact strength parameter (Pressure exponent)

EPSI

Reference Strain Rate

T

Maximum Tensile Strength

SFMAX

Maximum normalized Fractured Strength

HEL

Hugoniot elastic limit

PHEL

Pressure component at the at Hugoniot elastic limit

BETA

Fraction of elastic energy loss converted to hydrostatic energy

Di

Parameters for plastic strain to fracture

K1, K2

First and Second pressure coefficients

178 Materials

Field

Comments

K3

Elastic Constant (Note that K1 is the bulk modulus)

FS

Failure Criteria <0: Fails if (p* + t*) is negative (tensile failure) 0: No failure >0: Fails if strain exceeds FS

See Also: • LS-DYNA Keyword User’s Manual MAT_JOHNSON_HOLMQUIST_CONCRETE This material model is used for concrete under high strain rates, large strains and high pressure.

Field

Comments

Title

Unique name identifying material model

Desc

Optional description of the material model

TITLE_OPTION

If selected material title option is used

MID

Material identification number (Integer > 0)

RO

Mass Density of the material

G

Shear Modulus

A

Normalized Cohesive Strength

B

Normalized Pressure Hardening

C

Strain rate coefficient

N

Pressure Hardening Exponent

Materials 179 Materials

Field

Comments

FC

Quasi-static uniaxial compressive strength

T

Maximum Tensile hydrostatic pressure

EPSO

Reference Strain Rate

EFMIN

Plastic strain before fracture

SFMAX

Maximum Fractured Strength

PC

Crushing Pressure

UC

Crushing Volumetric Strain

PL

Locking Pressure

UL

Locking Volumetric Strain

D1, D2

Damage Constants

K1, K2, K3

Pressure Constants

FS

Failure Type

See Also: • LS-DYNA Keyword User’s Manual MAT_FINITE_ELASTIC_STRAIN_PLASTICITY An elasto-plastic material model with arbitrary stress-strain curve and arbitrary strain rate dependency. This material model uses a finite strain formulation allowing large elastic strains before yielding.

Field

Comments

Title

Unique name identifying material model

Desc

Optional description of the material model

TITLE_OPTION

If selected material title option is used

MID

Material identification number (Integer > 0)

RO

Mass Density of the material

180 Materials

Field

Comments

E

Young’s Modulus

PR

Poisson’s Ratio

SIGY

Yield Stress

ETAN

Tangent Modulus

FAIL

Failure Flag <0: User defined failure subroutine is called to determine failure =0: Failure is not considered. >0: Plastic strain to failure. When plastic strain reaches this value, the element is deleted from calculation.

TDEL

Minimum time step size for automatic element deletion

C, P

Strain Rate Parameters

LCSS

Load Curve Id for effective Stress vs. effective plastic Strain

LCSR

Load Curve Id defining Strain Rate Effect on Yield Stress

See Also: • LS-DYNA Keyword User’s Manual MAT_LAYERED_LINEAR_PLASTICITY Defines a layered elastoplastic material with an arbitrary stress-strain curve and arbitrary strain rate dependency.

Field

Comments

Title

Unique name identifying material model

Desc

Optional description of the material model

Materials 181 Materials

Field

Comments

TITLE_OPTION

If selected material title option is used

MID

Material identification number (Integer > 0)

RO

Mass Density of the material

E

Young’s Modulus

PR

Poisson’s Ratio

SIGY

Yield Stress

ETAN

Tangent Modulus

FAIL

Failure Flag <0: User defined failure subroutine is called to determine failure =0: Failure is not considered. >0: Plastic strain to failure. When plastic strain reaches this value, the element is deleted from calculation.

TDEL

Minimum time step size for automatic element deletion

C, P

Strain Rate Parameters

LCSS

Load Curve Id for effective Stress vs. effective plastic Strain

LCSR

Load Curve Id defining Strain Rate Effect on Yield Stress

See Also: • LS-DYNA Keyword User’s Manual MAT_UNIFIED_CREEP Defines properties of a material for elastic creep behavior.

Field

Comments

Title

Unique name identifying material model

Desc

Optional description of the material model

TITLE_OPTION

If selected material title option is used

182 Materials

Field

Comments

MID

Material identification number (Integer > 0)

RO

Mass Density of the material

E

Young’s Modulus

PR

Poisson’s Ratio

A

Stress Coefficient

N

Stress Exponent

M

Time Exponent

See Also: • LS-DYNA Keyword User’s Manual MAT_COMPOSITE_LAYUP Defines the elastic response of composite layups that have an arbitrary number of layers through the shell thickness.

Field

Comments

Title

Unique name identifying material model

Desc

Optional description of the material model

TITLE_OPTION

If selected material title option is used

MID

Material identification number (Integer > 0)

RO

Mass Density of the material

EA

Young’s Modulus, a Direction

Materials 183 Materials

Field

Comments

EB

Young’s Modulus, b Direction

EC

Young’s Modulus, c Direction

PRBA, PRCA, PRCB

Poisson’s Ratio in the ba, ca and cb directions

GAB, GBC, GCA

Shear Moduli in the ab, bc and ca directions

AOPT

Material Axes option 0: Locally orthotropic with material axes determined by element nodes 1, 2, and 4. (Node 1 is the local origin, Node 2 is along the local a- axis; Local c-axis is the cross product of local a-axis, and the vector from node 1 to node 4; Local b- axis is the cross product of loca c- and a- axes.) 1: Locally orthotropic with material axis determined by a point in space, and the global location of the element center; this is the a- direction. This option is for solid elements only. 2: Globally orthotropic with material axis determined by3 vectors below. 3: Locally orthotropic with material axis determined by rotating the material axes about the element normal by an angle, BETA, from a line in the plane of the element defined by the cross product of the vector v with the element normal. 4: Locally orthotropic in cylindrical coordinate system with the material axis determined by a vector v, and an originating point, P, which defines the centerline axis. This option is for solid elements only.

XP, YP, ZP

Coordinates of point p for AOPT=1 and 4

Ai

Component of Vector a, for AOPT=2

Vi

Component of Vector v, for AOPT=3 and 4

Di

Component of Vector d, for AOPT=2

BETA

Material Angle (Degrees), for AOPT=3

See Also: • LS-DYNA Keyword User’s Manual

184 Materials

MAT_COMPOSITE_MATRIX Defines the properties of materials used for the elastic response of composites where pre-integration is used to compute the extensional, bending, and coupling stiffness coefficients (available only for Belytschko-Tsay resultant shell formulation).

Field

Comments

Title

Unique name identifying material model

Desc

Optional description of the material model

TITLE_OPTION

If selected material title option is used

MID

Material identification number (Integer > 0)

RO

Mass Density of the material

Cij

Coefficient of Stiffness Matrix

Materials 185 Materials

Field AOPT

Comments Material Axes option 0: Locally orthotropic with material axes determined by element nodes 1, 2, and 4. (Node 1 is the local origin, Node 2 is along the local a- axis; Local c-axis is the cross product of local a-axis, and the vector from node 1 to node 4; Local b- axis is the cross product of loca c- and a- axes.) 1: Locally orthotropic with material axis determined by a point in space, and the global location of the element center; this is the a- direction. This option is for solid elements only. 2: Globally orthotropic with material axis determined by3 vectors below. 3: Locally orthotropic with material axis determined by rotating the material axes about the element normal by an angle, BETA, from a line in the plane of the element defined by the cross product of the vector v with the element normal. 4: Locally orthotropic in cylindrical coordinate system with the material axis determined by a vector v, and an originating point, P, which defines the centerline axis. This option is for solid elements only.

XP, YP, ZP

Coordinates of point p for AOPT=1 and 4

Ai

Component of Vector a, for AOPT=2

Vi

Component of Vector v, for AOPT=3 and 4

Di

Component of Vector d, for AOPT=2

BETA

Material Angle (Degrees), for AOPT=3

See Also: • LS-DYNA Keyword User’s Manual

186 Materials

MAT_COMPOSITE_DIRECT Defines properties for a material used for the elastic response of composites where pre-integration is used to compute the extensional, bending, and coupling stiffness coefficients (available only for BelytschkoTsay resultant shell formulation).

Field

Comments

Title

Unique name identifying material model

Desc

Optional description of the material model

TITLE_OPTION

If selected material title option is used

MID

Material identification number (Integer > 0)

RO

Mass Density of the material

Cij

Coefficient of Stiffness Matrix

See Also: • LS-DYNA Keyword User’s Manual

Materials 187 Materials

MAT_GENERAL_NONLINEAR_6DOF_DISCRETE_BEAM Defines the properties of a very general spring and damper. The beam is based on MAT_SPRING_GENERAL_NONLINEAR option. This model includes additional unloading options.

Field

Comments

Title

Unique name identifying material model

Desc

Optional description of the material model

TITLE_OPTION

If selected material title option is used

MID

Material identification number (Integer > 0)

RO

Mass Density of the material

KT

Translational stiffness for unloading option 2.0

KR

Rotational Stiffness for unloading option 2.0

UNLDOPT

Unloading Option

OFFSET

Offset Factor (between 0 and 1)

188 Materials

Field

Comments

DAMPF

Damping factor for stability

LCIDTR, LCIDTS, LCIDTT

Load Curve Id defining Translational Force resultant along r, s, t axes respectively vs. Translational Displacement.

LCIDRR, LCIDRS, LCIDRT

Load Curve Id defining Rotational Moment about r, s, t axes vs. Rotational Displacement.

LCIDTUR, LCIDTUS, LCIDTUT

Load Curve Id defining Translational Force resultant along r, s, t axes vs. Translational Displacement during unloading

LCIDRUR, LCIDRUS, LCIDRUT

Load Curve Id defining Rotational Moment about r, s, t axes vs. Rotational Displacement during unloading.

LCIDTDR, LCIDTDS, LCIDTDT

Load Curve Id defining Translational Damping Force along r, s, t axes vs. relative Translational Velocity.

LCIDRDR, LCIDRDS, LCIDRDT

Load Curve Id defining Rotational Damping Moment about r, s, t axes vs. relative Rotational Velocity.

LCIDTER, LCIDTES, LCIDTET

Load Curve Id defining Translational Damping Force scale factor vs. relative Displacement along r, s, t axes

LCIDRER, LCIDRES, LCIDRER

Load Curve Id defining Rotational Damping Moment scale factor vs. relative Displacement along r, s, t axes

UTFAILR, UTFAILS, UTFAILT

Translational Displacement along r, s, t at failure in Tension

WTFAILR, WTFAILS, WTFAILT

Rotational Displacement about r, s, t at failure in Tension

UCFAILR, UCFAILS, UCFAILT

Translational Displacement along r, s, t at failure in Compression

WCFAILR, WCFAILS, WCFAILT

Rotational Displacement about r, s, t at failure in Compression

IUR, IUS< IUT

Initial Translational Displacement along r, s, t directions

IWR, IWS, IWT

Initial Rotational Displacement about r, s, t axes

See Also: • LS-DYNA Keyword User’s Manual

Materials 189 Materials

MAT_GURSON Defines the material properties for the Gurson dilational plastic material model (available only for shell elements).

Field

Comments

Title

Unique name identifying material model

Desc

Optional description of the material model

TITLE_OPTION

If selected material title option is used

MID

Material identification number (Integer > 0)

RO

Mass Density of the material

E

Young’s Modulus

PR

Poisson’s Ratio

SIGY

Yield Stress

N

Exponent in power law

Q1, Q2

Parameters

FC

Critical void volume fraction

F0

Initial void volume fraction

EN

Mean nucleation strain

SN

Standard deviation SN of the normal distribution of εN

FN

Void Volume Fraction of nucleating particles

ETAN

Hardening Modulus

190 Materials

Field ATYP

Comments Hardening Type 1: Power Law 2: Linear 3: 8 points curve

FF0

Failure void volume fraction

Li

Element Length Value

FFi

Corresponding failure void volume fraction

LCSS

Load Curve id defining effective Stress vs. effective plastic Strain

LCLF

Load Curve Id defining Failure Void Volume Fraction vs. Element Length

NUMINT

No of through thickness integration points which must fail before element is deleted

LCF0

Lod curve Id defining initial void volume fraction f0 vs. element length.

LCFC

Lod curve Id defining initial void volume fraction fN vs. element length.

LCFN

Lod curve Id defining initial void volume fraction f0 vs. element length.

VGTYP

Type of void growth behavior: .EQ. 0: void growth in tension, and void contraction in compression, but never below f0 (default). .EQ. 1: void growth in tension only. .EQ. 2: void growth in tension, and void contraction in compression, even below f0.

See Also: • LS-DYNA Keyword User’s Manual

Materials 191 Materials

MAT_GURSON_RCDC Defines the material properties for the Gurson model with Wilkins Rc-Dc (for shell elements only).

Field

Comments

Title

Unique name identifying material model

Desc

Optional description of the material model

TITLE_OPTION

If selected material title option is used

MID

Material identification number (Integer > 0)

RO

Mass Density of the material

E

Young’s Modulus

PR

Poisson’s Ratio

SIGY

Yield Stress

N

Exponent in power law

Q1, Q2

Parameters

FC

Critical void volume fraction

F0

Initial void volume fraction

EN

Mean nucleation strain

SN

Standard deviation SN of the normal distribution of εN

FN

Void Volume Fraction of nucleating particles

192 Materials

Field

Comments

ETAN

Hardening Modulus

ATYP

Hardening Type 1: Power Law 2: Linear 3: 8 points curve

FF0

Failure void volume fraction

Li

Element Length Value

FFi

Corresponding failure void volume fraction

LCSS

Load Curve id defining effective Stress vs. effective plastic Strain

LCLF

Load Curve Id defining Failure Void Volume Fraction vs. Element Length

NUMINT

No of through thickness integration points which must fail before element is deleted

ALPHA

Parameter α for Rc-Dc Model

BETA

Parameter β for Rc-Dc Model

GAMMA

Parameter γ for Rc-Dc Model

D0

Parameter D0 for Rc-Dc Model

B

Parameter b for Rc-Dc Model

LAMBDA

Parameter λ for Rc-Dc Model

DS

Parameter ds for Rc-Dc Model

L

Characteristic element length for Rc-Dc Material

See Also: • LS-DYNA Keyword User’s Manual

Materials 193 Materials

MAT_GENERAL_NONLINEAR_1DOF_DISCRETE_BEAM Defines the material properties for a very general spring and damper. The beam is based on MAT_SPRING_GENERAL_NONLINEAR option and is a one dimensional version of 6DOF_DESCRETE_BEAM. This model includes additional unloading options.

Field

Comments

Title

Unique name identifying material model

Desc

Optional description of the material model

TITLE_OPTION

If selected material title option is used

MID

Material identification number (Integer > 0)

RO

Mass Density of the material

K

Translational stiffness for unloading option 2

UNLDOPT

Unloading option

OFFSET

Offset to determine permanent set upon unloading if the UNLDOPT equals to 3.

DAMPF

Damping factor for stability

LCIDT

Load Curve Id defining Translational Force along the axis vs. relative Translational Displacement.

LCIDTU

Load Curve Id defining Translational Force along the axis vs. relative Translational Displacement, during unloading

LCIDTD

Load Curve Id defining Translational Damping Force along the local axis vs. relative Translational Velocity.

LCIDTE

Load Curve Id defining Translational Damping Force scale factor along the local axis vs. relative Displacement.

UTFAIL

Translational displacement at failure in tension

194 Materials

Field

Comments

UCFAIL

Translational displacement at failure in compression

IU

Initial translational displacement along the axis

See Also: • LS-DYNA Keyword User’s Manual MAT_HILL_3R Defines the properties for the Hill’s planar anisotropic material model with 3 R values.

Field

Comments

Title

Unique name identifying material model

Desc

Optional description of the material model

TITLE_OPTION

If selected material title option is used

MID

Material identification number (Integer > 0)

RO

Mass Density of the material

E

Young’s Modulus

PR

Poisson’s Ratio

Materials 195 Materials

Field HR

Comments Hardening Rule 1: Linear 2: Exponential 3: Load Curve

P1, P2

Material Parameters

R00, R45, R90

Lankford parameters

LCID

Load Curve Id for the hardening rule

Epsilon_0

ε0 for determining initial yield stress for exponential hardening

SPI

Parameter to redefine ε0

AOPT

Material Axes option 0: Locally orthotropic with material axes determined by element nodes 1, 2, and 4. (Node 1 is the local origin, Node 2 is along the local a- axis; Local c-axis is the cross product of local a-axis, and the vector from node 1 to node 4; Local b- axis is the cross product of loca c- and a- axes.) 1: Locally orthotropic with material axis determined by a point in space, and the global location of the element center; this is the a- direction. This option is for solid elements only. 2: Globally orthotropic with material axis determined by3 vectors below. 3: Locally orthotropic with material axis determined by rotating the material axes about the element normal by an angle, BETA, from a line in the plane of the element defined by the cross product of the vector v with the element normal.

blank1, blank2, blank3

Blank Fields

Ai

Component of Vector a, for AOPT=2

Vi

Component of Vector v, for AOPT=3

Di

Component of Vector d, for AOPT=2

BETA

Material Angle (Degrees), for AOPT=3

See Also: • LS-DYNA Keyword User’s Manual

196 Materials

MAT_MODIFIED_PIECEWISE_LINEAR_PLASTICITY Defines an elasto-plastic material with an arbitrary stress versus strain curve and arbitrary strain rate dependency (available only for shell elements).

Field

Comments

Title

Unique name identifying material model

Desc

Optional description of the material model

TITLE_OPTION

If selected material title option is used

MID

Material identification number (Integer > 0)

RO

Mass Density of the material

E

Young’s Modulus

PR

Poisson’s Ratio

SIGY

Yield Stress

ETAN

Tangent Modulus

FAIL

Failure flag

TDEL

Minimum time step size for automatic element deletion

C, P

Strain Rate Parameters

LCSS

Load Curve Id defining effective Stress vs. effective plastic Strain

LCSR

Load Curve Id defining Strain Rate scaling effect on Yield Stress

VP

Formulation for Rate Effects

EPSTHIN

Thinning Plastic Strain at Failure

EPSMAJ

Major Plastic Strain at Failure

NUMINT

No. of through thickness integration points that must fail before element is deleted

See Also: • LS-DYNA Keyword User’s Manual

Materials 197 Materials

MAT_PLASTICITY_COMPRESSION_TENSION Defines an isotropic elastic-plastic material allowing different yield stress versus plastic strain curves in compression and tension.

Field

Comments

Title

Unique name identifying material model

Desc

Optional description of the material model

TITLE_OPTION

If selected material title option is used

MID

Material identification number (Integer > 0)

RO

Mass Density of the material

E

Young’s Modulus

PR

Poisson’s Ratio

C, P

Strain Rate Parameters

FAIL

Failure Flag

TDEL

Minimum time step size for automatic element deletion

LCIDC

Load Curve Id defining Yield Stress vs. effective Plastic Strain in compression

LCIDT

Load Curve Id defining Yield Stress vs. effective Plastic Strain in tension

198 Materials

Field

Comments

LCSRC

Optional load curve Id defining strain rate scaling effect on yield stress when the material is in compression

LCSRT

Optional load curve Id defining strain rate scaling effect on yield stress when the material is in tension

SRFLAG

Formulation for rate effects: .EQ. 0: Total strain rate ; .EQ. 1: Deviatoric strain rate

LCFAIL

Load curve Id defining failure strain vs. strain rate

PC

Compressive mean stress (pressure) at which the yield stress follows the Load Curve ID, LCIDC

PT

Tensile mean stress (pressure) at which the yield stress follows the Load Curve ID, LCIDT

PCUTC

Pressure cut-off in compression

PCUTT

Pressure cut-off in tension

PCUTF

Pressure cut-off flag: 0 = inactive ; 1 = active

K

(optional) bulk modulus for the viscoelastic material. If nonzero, a Kelvin type will be used.

NUM_RFS

Number of terms used for shear relaxationmodulus/shear decay constant

GI1

(optional) shear relaxation modulus for the i-th term

BETAI1

(optional) shear decay constant for the i-th term

See Also: • LS-DYNA Keyword User’s Manual

Materials 199 Materials

MAT_MODIFIED_HONEYCOMB Defines the properties for aluminum honeycomb crushable foam materials with anisotropic behavior.

Field

Comments

Title

Unique name identifying material model

Desc

Optional description of the material model

TITLE_OPTION

If selected material title option is used

MID

Material identification number (Integer > 0)

RO

Mass Density of the material

E

Young’s Modulus

PR

Poisson’s Ratio

SIGY

Yield Stress

VF

Relative volume at which honeycomb is fully compacted

MU

Material viscosity coefficient

BULK

Bulk Viscosity Flag 0: Not used 1: Active and MU=0

200 Materials

Field LCA

Comments Load Curve ID, defining: >0: Stress along a- axis vs. strain along a-axis <0: Yield stress vs. the angle off the material axis is degrees

LCB

Load Curve ID, defining: >0: Stress along b- axis vs. strain along b-axis <0: the strong axis stress vs. volumetric strain

LCC

Load Curve ID, defining: >0: Stress along c- axis vs. strain along c-axis <0: the wreak axis stress vs. volumetric strain

LCS

Load Curve ID, defining: >0: Shear Stress vs. shear strain <0: the damage curve defining the shear stress multiplier as a function of the shear strain component

LCAB

Load Curve ID, defining: >0: Shear Stress-ab vs. shear strain-ab <0: the damage curve defining the shear stress-ab multiplier as a function of the shear strain-ab

LCBC

Load Curve ID, defining: >0: Shear Stress-bc vs. shear strain-bc <0: the damage curve defining the shear stress-bc multiplier as a function of the shear strain-bc

LCCA

Load Curve ID, defining: >0: Shear Stress-ca vs. shear strain-ca <0: the damage curve defining the shear stress-ca multiplier as a function of the shear strain-ca

LCSR

Load Curve ID of Strain Rate effect scale factor vs. Strain Rate

EAAU, EBBU, ECCU

Elastic Moduli in the a-, b-, and c- directions, in uncompressed configuration

GABU, GBCU, GCAU

Shear Moduli in the ab, bc, ca planes in uncompressed configuration

Materials 201 Materials

Field AOPT

Comments Material Axes option 0: Locally orthotropic with material axes determined by element nodes 1, 2, and 4. (Node 1 is the local origin, Node 2 is along the local a- axis; Local c-axis is the cross product of local a-axis, and the vector from node 1 to node 4; Local b- axis is the cross product of loca c- and a- axes.) 1: Locally orthotropic with material axis determined by a point in space, and the global location of the element center; this is the a- direction. This option is for solid elements only. 2: Globally orthotropic with material axis determined by3 vectors below. 3: Locally orthotropic with material axis determined by rotating the material axes about the element normal by an angle, BETA, from a line in the plane of the element defined by the cross product of the vector v with the element normal. 4: Locally orthotropic in cylindrical coordinate system with the material axis determined by a vector v, and an originating point, P, which defines the centerline axis. This option is for solid elements only.

MSCF

Material axes change flag: 1 = no change (default) ; 2 = switch material axes a and b 3 = switch material axes a and c ; 4 = switch material axes b and c

XP

X-coordinate of point p for AOPT=1

YP

Y-coordinate of point p for AOPT=1

ZP

Z-coordinate of point p for AOPT=1

Ai

Component of Vector a, for AOPT=2

Di

Component of Vector d, for AOPT=2

TSEF

Tensile Strain at Element Failure

SSEF

Shear Strain at Element Failure

VREF

Relative volume at which the reference geometry is stored (for solid elements 1, 2, 3, 4, 10)

202 Materials

Field

Comments

TREF

Element timestep size at which the reference geometry is stored

SHDFLG

Flag defining treatment of damage from curves LCS, LCAB, LCBC, and LCBC (relevant only if LCA < 0): .EQ. 0: damage reduces shear stress every time step .EQ. 1: damage = (shear stress)/(undamaged shear stress)

See Also: • LS-DYNA Keyword User’s Manual MAT_ARRIBA_BOYCE_RUBBER Defines the material properties for hyperelastic rubber combined optionally with linear viscoelasticity.

Field

Comments

Title

Unique name identifying material model

Desc

Optional description of the material model

TITLE_OPTION

If selected material title option is used

MID

Material identification number (Integer > 0)

RO

Mass Density of the material

K

Bulk Modulus

G

Shear Modulus

N

Number of statistical links

Materials 203 Materials

Field

Comments

LCID

Load Curve id defining Relaxation curve for shear

TRAMP

Optional ramp time for loading

NT

Number of Prony series terms in fit

NUM_RFS

Number of viscoelastic constants

GIi

Optional i-th shear Relaxation Modulus i

BETAIi

Optional i-th shear Decay Constant

See Also: • LS-DYNA Keyword User’s Manual MAT_HEART_TISSUE Defines the material properties for heart tissue as described in the paper by Guccione, McCulloch and Waldman [1991]. This model is transversely anisotropic.

Field

Comments

Title

Unique name identifying material model

Desc

Optional description of the material model

TITLE_OPTION

If selected material title option is used

MID

Material identification number (Integer > 0)

RO

Mass Density of the material

C, B1, B2, B3

Material Coefficients

204 Materials

Field

Comments

P

Pressure in muscle tissue

AOPT

Material Axes option 0: Locally orthotropic with material axes determined by element nodes 1, 2, and 4. (Node 1 is the local origin, Node 2 is along the local a- axis; Local c-axis is the cross product of local a-axis, and the vector from node 1 to node 4; Local b- axis is the cross product of loca c- and a- axes.) 1: Locally orthotropic with material axis determined by a point in space, and the global location of the element center; this is the a- direction. This option is for solid elements only. 2: Globally orthotropic with material axis determined by3 vectors below. 3: Locally orthotropic with material axis determined by rotating the material axes about the element normal by an angle, BETA, from a line in the plane of the element defined by the cross product of the vector v with the element normal. 4: Locally orthotropic in cylindrical coordinate system with the material axis determined by a vector v, and an originating point, P, which defines the centerline axis. This option is for solid elements only.

MACF

Material axes change flag: 1 = no change (default) ; 2 = switch material axes a and b 3 = switch material axes a and c ; 4 = switch material axes b and c

XP, YP, ZP

Coordinates of point p for AOPT=1 and 4

Ai

Component of Vector a, for AOPT=2

Vi

Component of Vector v, for AOPT=3 and 4

Di

Component of Vector d, for AOPT=2

BETA

Material Angle (Degrees), for AOPT = 3

See Also: • LS-DYNA Keyword User’s Manual

Materials 205 Materials

MAT_LUNG_TISSUE Defines the material properties for a hyperelastic material model for heart tissue combined optionally with linear viscoelasticity.

Field

Comments

Title

Unique name identifying material model

Desc

Optional description of the material model

TITLE_OPTION

If selected material title option is used

MID

Material identification number (Integer > 0)

RO

Mass Density of the material

K

Bulk Modulus

C, DELTA, ALPHA, BETA, C1, C2

Material Coefficients

LCID

Relaxation curve for shear

TRAMP

Optional ramp time for loading

NT

Number of Prony series terms in fit

NUM_RFS

Number of viscoelastic constants

GIi

Optional i-th shear Relaxation Modulus

BETAIi

Optional i-th shear Decay Constant

See Also: • LS-DYNA Keyword User’s Manual

206 Materials

MAT_SPECIAL_ORTHOTROPIC This material model defines the properties for a material model developed for the Belytschko-Tsay and the C0 triangle shell elements. It is based on a resultant stress formulation. In plane behavior is treated separately from bending in order to model perforated materials such as television shadow masks.

Field

Comments

Title

Unique name identifying material model

Desc

Optional description of the material model

TITLE_OPTION

If selected material title option is used

MID

Material identification number (Integer > 0)

RO

Mass Density of the material

YS

Yield Stress

EP

Plastic Hardening Modulus

EiiP

Young’s Modulus (in-plane) in i- direction

NUijP

Poisson’s Ratio in plane ij

GijP

Shear Modulus in Plane ij

EiiB

Young’s Modulus (Bending) in i-direction

NUijB

Poisson’s Ratio (Bending) in ij plane

G12B

Shear Modulus (Bending) in 12 plane

Materials 207 Materials

Field AOPT

Comments Material Axes option 0: Locally orthotropic with material axes determined by element nodes 1, 2, and 4. (Node 1 is the local origin, Node 2 is along the local a- axis; Local c-axis is the cross product of local a-axis, and the vector from node 1 to node 4; Local b- axis is the cross product of loca c- and a- axes.) 1: Locally orthotropic with material axis determined by a point in space, and the global location of the element center; this is the a- direction. This option is for solid elements only. 2: Globally orthotropic with material axis determined by3 vectors below. 3: Locally orthotropic with material axis determined by rotating the material axes about the element normal by an angle, BETA, from a line in the plane of the element defined by the cross product of the vector v with the element normal.

blank i

Blank Field

Ai

Component of Vector a, for AOPT=2

Vi

Component of Vector v, for AOPT=3

Di

Component of Vector d, for AOPT=2

BETA

Material angle (degrees), for AOPT = 3

See Also: • LS-DYNA Keyword User’s Manual

208 Materials

MAT_MODIFIED_FORCE_LIMITED This material model is an extension of MAT_FORCE_LIMITED (MAT_029). In addition to plastic hinge and collapse mechanisms, yield moments may be defined as a function of axial force. The moment transmitted by the hinge is defined by a moment-plastic rotation relationship.

Materials 209 Materials

210 Materials

Field

Comments

Title

Unique name identifying material model

Desc

Optional description of the material model

TITLE_OPTION

If selected material title option is used

MID

Material identification number (Integer > 0)

RO

Mass Density of the material

E

Young’s Modulus

PR

Poisson’s Ratio

Materials 211 Materials

Field

Comments

DF

Damping Factor

AOPT

Axial load curve option 0: Force vs. Strain 1: Force vs. change in length

YTFLAG

Flag to allow beam to yield

ASOFT

Axial elastic softening factor

M1, M2, ..., M8

Applied End Moments

LC1, LC2, ..., LC8

Load Curve Ids corresponding to applied end moments

LPSi

Load Curve Id for plastic moment vs. rotation about s-axis at node i

SFSi

Scale factor, plastic moment vs. rotation about s- axis at node i

YMSi

Yield moment about s- axis at node i for interaction calculations

LPTi

Load Curve Id for plastic moment vs. rotation about t-axis at node i

SFTi

Scale factor, plastic moment vs. rotation about t- axis at node i

YMTi

Yield moment about t- axis at node i for interaction calculations

LPR

Load Curve Id for plastic torsional moment vs. rotation

SFR

Load Curve Id for Scale factor vs. rotation

YMR

Torsional Yield moment for interaction calculation

LYSi

Load Curve Id for yield moment vs. axial force along axis s at node i

SYSi

Load Curve Id for Scale factor applied to corresponding load curve LYSi

LYTi

Load Curve Id for yield moment vs. axial force along axis t at node i

SYTi

Load Curve Id for Scale factor applied to corresponding load curve LYTi

LYR

Load Curve Id for yield moment vs. axial force for the torsional axis

LYS

Load Curve Id for the Scale factor applying to LYR

HMS1_i

Hinge moments for s axis at node 1 for hinge i

LPMS1_i

Load Curve Id for plastic moment vs. plastic rotation for HMS1_i

HMS2_i

Hinge moments for s axis at node 2 for hinge i

LPMS2_i

Load Curve Id for plastic moment vs. rotation for HMS2_i

HMT1_i

Hinge moments for t axis at node 1 for hinge i

LPMT1_i

Load Curve Id for plastic moment vs. rotation for HMT1_i

HMT2_i

Hinge moments for t axis at node 2 for hinge i

LPMT2_i

Load Curve Id for plastic moment vs. rotation for HMT2_i

212 Materials

Field

Comments

HMR_i

Hinge moment for the torsional axis for hinge i

LPMR_i

Load Curve Id for plastic moment vs. plastic rotation for HMR_i

See Also: • LS-DYNA Keyword User’s Manual MAT_VACUUM Defines the properties for a dummy material representing a vacuum in a multi-material Euler/ALE model.

Field

Comments

Title

Unique name identifying material model

Desc

Optional description of the material model

TITLE_OPTION

If selected material title option is used

MID

Material identification number (Integer > 0)

KW_OPTION

Title optional keywords

See Also: • LS-DYNA Keyword User’s Manual

Materials 213 Materials

MAT_RATE_SENSITIVE_POLYMER Defines the properties for simulating an isotropic ductile polymer with strain rate effects. It uses uniaxial test data.

Field

Comments

Title

Unique name identifying material model

Desc

Optional description of the material model

TITLE_OPTION

If selected material title option is used

MID

Material identification number (Integer > 0)

RO

Mass Density of the material

E

Young’s Modulus

PR

Poisson’s Ratio

D0

Reference Strain Rate (D0)

N

Exponent for inelastic strain rate

Z0

Initial hardness of material (Z0)

q

Parameter used in the constitutive equation

Omega

Maximum internal stress

See Also: • LS-DYNA Keyword User’s Manual

214 Materials

MAT_TRANSVERSELY_ANISOTROPIC_CRUSHABLE_FOAM Defines the properties for extruded foam material that is transversely anisotropic, crushable, and of low density with no significant Poisson effect.

Field

Comments

Title

Unique name identifying material model

Desc

Optional description of the material model

TITLE_OPTION

If selected material title option is used

MID

Material identification number (Integer > 0)

RO

Mass Density of the material

E11, E22

Elastic Moduli in the 1(axial) and 2 (transverse) direction

E12

Elastic shear Modulus in the axial-transverse plane (E12 = E13)

G

Shear Modulus

K

Bulk Modulus for Contact Stiffness

I11

Load Curve Id for Nominal Axial Stress vs. Volumetric Strain

I22

Load Curve Id for Nominal Transverse Stress vs. Volumetric Strain (I22= I33)

I12

Load Curve Id for Shear Stress components 12 and 31 vs. Volumetric Strain (I22= I31)

I23

Load Curve Id for Shear Stress components 23 vs. Volumetric Strain

Materials 215 Materials

Field

Comments

IAA

Load Curve Id for Nominal stress vs. Volumetric strain at angle, ANG, relative to the material axis

NY

Flag for symmetric yield surface

ANG

Angle corresponding to Load Curve Id, IAA

MU

Damping factor

AOPT

Material Axes option 0: Locally orthotropic with material axes determined by element nodes 1, 2, and 4. (Node 1 is the local origin, Node 2 is along the local a- axis; Local c-axis is the cross product of local a-axis, and the vector from node 1 to node 4; Local b- axis is the cross product of loca c- and a- axes.) 1: Locally orthotropic with material axis determined by a point in space, and the global location of the element center; this is the a- direction. This option is for solid elements only. 2: Globally orthotropic with material axis determined by3 vectors below.

ISCL

Load Curve Id for the strain rate scale factor vs. volumetric strain rate. The yield rate is scaled by the value specified by the load curve.

MSCF

Material axes change flag: 1 = no change (default) ; 2 = switch material axes a and b 3 = switch material axes a and c ; 4 = switch material axes b and c

XP

X-coordinate of point p for AOPT=1

YP

Y-coordinate of point p for AOPT=1

ZP

Z-coordinate of point p for AOPT=1

Ai

Component of Vector a, for AOPT=2

Vi

Components of vector v (for AOPT = 3 or 4)

Di

Component of Vector d, for AOPT=2

See Also: • LS-DYNA Keyword User’s Manual

216 Materials

MAT_WOOD Defines the material properties for a transversely isotropic material (available only for solid elements).

Field

Comments

Title

Unique name identifying material model

Desc

Optional description of the material model

TITLE_OPTION

If selected material title option is used

MID

Material identification number (Integer > 0)

RO

Mass Density of the material

Materials 217 Materials

Field NPLOT

Comments Plotting Option 1: Parallel damage 2: Perpendicular damage

ITER

Number of plasticity algorithm iterations

IRATE

Rate effects option 0: Turn off 1: Turn on

HARD

Perfect plasticity override

IFAIL

Erosion perpendicular to the ground 0: No 1: Yes

IVOL

Erode on negative volume or strain increments greater than 0.01 =0 No (default) ; =1 Yes

EL

Parallel Normal Modulus

ET

Perpendicular Normal Modulus

GLT

Parallel Shear Modulus (GLT=GLR)

GTR

Perpendicular Shear Modulus

PR

Poisson’s Ratio

XT

Parallel Tensile Strength

XC

Parallel Compressive Strength

YT

Perpendicular Tensile Strength

YC

Perpendicular Compressive Strength

SXY

Parallel Shear Strength

SYZ

Perpendicular Shear Strength

GF1_I

Parallel Fracture Energy in Tension

GF2_I

Parallel Fracture Energy in Shear

BFIT

Parallel softening Parameter

DMAX_I

Parallel Maximum Damage

GF1_r

Perpendicular Fracture Energy in Tension

GF2_r

Perpendicular Fracture Energy in Shear

218 Materials

Field

Comments

DFIT

Perpendicular Softening Parameter

DMAX_r

Perpendicular Maximum Damage

FLPAR

Parallel Fluidity Parameter for Tension and Shear

FLPARC

Parallel Fluidity Parameter for Compression

POWPAR

Parallel Power

FLPER

Perpendicular Fluidity Parameter for Tension and Shear

FLPERC

Perpendicular Fluidity Parameter for Compression

POWPER

Perpendicular Power

NPAR

Parallel Hardening initiation

CPAR

Parallel Hardening Rate

NPER

Perpendicular Hardening initiation

CPER

Perpendicular Hardening Rate

AOPT

Material Axes option 0: Locally orthotropic with material axes determined by element nodes 1, 2, and 4. (Node 1 is the local origin, Node 2 is along the local a- axis; Local c-axis is the cross product of local a-axis, and the vector from node 1 to node 4; Local b- axis is the cross product of loca c- and a- axes.) 1: Locally orthotropic with material axis determined by a point in space, and the global location of the element center; this is the a- direction. This option is for solid elements only. 2: Globally orthotropic with material axis determined by3 vectors below.

MACF

Material axes change flag: =1 No Change; = 2 switch mateial axes a and b =3 switch material axes a and c ; =4 switch material axes b and c

BETA

Material angle in degrees (for AOP = 3)

XP

X-coordinate of point p for AOPT=1

YP

Y-coordinate of point p for AOPT=1

ZP

Z-coordinate of point p for AOPT=1

Ai

Component of Vector a, for AOPT=2

Di

Component of Vector d, for AOPT=2

Vi

Components of vector v( for AOP = 3 and 4)

Materials 219 Materials

See Also: • LS-DYNA Keyword User’s Manual MAT_WOOD_PINE Defines the material properties for a transversely isotropic material (available only for solid elements). This model has default material properties for yellow pine.

Field

Comments

Title

Unique name identifying material model

Desc

Optional description of the material model

TITLE_OPTION

If selected material title option is used

MID

Material identification number (Integer > 0)

RO

Mass Density of the material

NPLOT

Plotting Option 1: Parallel damage 2: Perpendicular damage

ITER

Number of plasticity algorithm iterations

220 Materials

Field IRATE

Comments Rate effects option 0: Turn off 1: Turn on

HARD

Perfect plasticity override

IFAIL

Erosion perpendicular to the ground 0: No 1: Yes

IVOL

Erode on negative volume or strain increments greater than 0.01 =0 No (default) ; =1 Yes

MOIS

Percentage moisture content

TEMP

Temperature

QUAL_T

Quality Factor Option in Tension

QUAL_C

Quality Factor Option in Compression

UNITS

Units Option 0: GPa, mm, msec, Kg/mm3, KN 1: MPa, mm, msec, g/mm3, N 2: MPa, mm, sec, Mg/mm3, N 3:Psi, inch, sec, lb-sec2/inch4, lb.

IQUAL

Apply quality factors perpendicular to grain 0: Yes 1: No

Materials 221 Materials

Field AOPT

Comments Material Axes option 0: Locally orthotropic with material axes determined by element nodes 1, 2, and 4. (Node 1 is the local origin, Node 2 is along the local a- axis; Local c-axis is the cross product of local a-axis, and the vector from node 1 to node 4; Local b- axis is the cross product of loca c- and a- axes.) 1: Locally orthotropic with material axis determined by a point in space, and the global location of the element center; this is the a- direction. This option is for solid elements only. 2: Globally orthotropic with material axis determined by3 vectors below.

MACF

Material axes change flag: =1 No Change; = 2 switch mateial axes a and b =3 switch material axes a and c ; =4 switch material axes b and c

BETA

Material angle in degrees (for AOP = 3)

XP

X-coordinate of point p for AOPT=1

YP

Y-coordinate of point p for AOPT=1

ZP

Z-coordinate of point p for AOPT=1

Ai

Component of Vector a, for AOPT=2

Di

Component of Vector d, for AOPT=2

Vi

Components of vector v( for AOP = 3 and 4)

See Also: • LS-DYNA Keyword User’s Manual

222 Materials

MAT_WOOD_FIR Defines the material properties for a transversely isotropic material (available only for solid elements). This model has default material properties for Douglas Fir.

Field

Comments

Title

Unique name identifying material model

Desc

Optional description of the material model

TITLE_OPTION

If selected material title option is used

MID

Material identification number (Integer > 0)

RO

Mass Density of the material

NPLOT

Plotting Option 1: Parallel damage 2: Perpendicular damage

ITER

Number of plasticity algorithm iterations

IRATE

Rate effects option 0: Turn off 1: Turn on

HARD

Perfect plasticity override

Materials 223 Materials

Field IFAIL

Comments Erosion perpendicular to the ground 0: No 1: Yes

IVOL

Erode on negative volume or strain increments greater than 0.01 =0 No (default) ; =1 Yes

MOIS

Percentage moisture content

TEMP

Temperature

QUAL_T

Quality Factor Option in Tension

QUAL_C

Quality Factor Option in Compression

UNITS

Units Option 0: GPa, mm, msec, Kg/mm3, KN 1: MPa, mm, msec, g/mm3, N 2: MPa, mm, sec, Mg/mm3, N 3:Psi, inch, sec, lb-sec2/inch4, lb.

IQUAL

Apply quality factors perpendicular to grain 0: Yes 1: No

AOPT

Material Axes option 0: Locally orthotropic with material axes determined by element nodes 1, 2, and 4. (Node 1 is the local origin, Node 2 is along the local a- axis; Local c-axis is the cross product of local a-axis, and the vector from node 1 to node 4; Local b- axis is the cross product of loca c- and a- axes.) 1: Locally orthotropic with material axis determined by a point in space, and the global location of the element center; this is the a- direction. This option is for solid elements only. 2: Globally orthotropic with material axis determined by3 vectors below.

MACF

Material axes change flag: =1 No Change; = 2 switch mateial axes a and b =3 switch material axes a and c ; =4 switch material axes b and c

224 Materials

Field

Comments

BETA

Material angle in degrees (for AOP = 3)

XP

X-coordinate of point p for AOPT=1

YP

Y-coordinate of point p for AOPT=1

ZP

Z-coordinate of point p for AOPT=1

Ai

Component of Vector a, for AOPT=2

Vi

Components of vector v( for AOP = 3 and 4)

Di

Component of Vector d, for AOPT=2

See Also: • LS-DYNA Keyword User’s Manual MAT_PITZER_CRUSHABLE_FOAM Defines the properties for a material model that simulates isotropic crushable foams with strain rate effects. It uses uniaxial and triaxial data.

Field

Comments

Title

Unique name identifying material model

Desc

Optional description of the material model

TITLE_OPTION

If selected material title option is used

MID

Material identification number (Integer > 0)

RO

Mass Density of the material

K

Bulk Modulus

G

Shear Modulus

PR

Poisson’s Ratio

TY

Tension Yield

SRTV

Young’s Modulus

LCPY

Load Curve Id defining pressure vs. volumetric strain

Materials 225 Materials

Field

Comments

LCUYS

Load Curve Id defining uniaxial stress vs. volumetric strain

LCRS

Load Curve Id defining Strain rate Scale Factor vs. Volumetric Strain rate

VC

Viscous Damping Coefficient

DFLG

Density Flag 0:Use Initial Density value 1: Use Current Density value

See Also: • LS-DYNA Keyword User’s Manual

226 Materials

MAT_SCHWER_MURRAY_CAP_MODEL Defines the material properties for a three invariant extension of MAT_GEOLOGIC_CAP_MODEL (MAT_025) that also includes viscoplasticity for rate effects and damage mechanics to model strain softening.

Field

Comments

Title

Unique name identifying material model

Desc

Optional description of the material model

TITLE_OPTION

If selected material title option is used

MID

Material identification number (Integer > 0)

RO

Mass Density of the material

SHEAR

Shear Modulus

BULK

Bulk Modulus

GRUN

Gruneisen Ratio

SHOCK

Shock Velocity Parameter

PORE

Flag for Pore Collapse 0: Yes 1: Constant Bulk Modulus

Materials 227 Materials

Field

Comments

ALPHA, THETA, GAMMA, BETA

Shear Failure Parameters

EFIT, FFIT

Dilitation damage mechanics parameters

ALPHAN, CALPHA

Kinematic strain hardening parameters

R0

Initial Gap Surface ellipticity, R

X0

Initial Gap Surface J1 (mean stress) axis intercept

IROCK

Material Flag 0: Soils (cap can contact) 1: Rock/Concrete

SECP

Shear Enhanced Compaction

AFIT, BFIT, RDAM0

Ductile damage mechanics parameters

W, D1, D2

Plastic volume strain parameters

NPLOT

History variable post-processed as effective plastic strain

EPSMAX

Maximum permitted strain increment

CFIT, DFIT

Brittle damage parameters

TFAIL

Tensile Failure Stress

FAILFL

Failure Flag (failed element)

DBETA, DDELTA

Rounded Vertices Parameters

VPTAU

Viscoplastic Relaxation time Parameter

ALPHA1 THETA1, GAMMA1, BETA1

Torsional scaling parameters

ALPHA2 THETA2, GAMMA2, BETA2

Triaxial extension scaling parameters

See Also: • LS-DYNA Keyword User’s Manual

228 Materials

MAT_1DOF_GENERALIZED_SPRING Defines the properties for a linear spring or damper that allows different degrees-of-freedom at two nodes to be coupled with linear spring and/or damper.

Field

Comments

Title

Unique name identifying material model

Desc

Optional description of the material model

TITLE_OPTION

If selected material title option is used

MID

Material identification number (Integer > 0)

RO

Mass Density of the material

K

Spring Stiffness

C

Damping Constant

SCLNi

Scale Factor on force at node i

DOFNi

Active dof at node i

CIDi

Local coordinate system Id at node 1 and node 2 respectively

See Also: • LS-DYNA Keyword User’s Manual

Materials 229 Materials

MAT_FHWA_SOIL Defines the material properties for an isotropic material with damage for solid elements. The model has a modified Mohr-Coulomb surface for determining pressure dependent peak shear strength.

Field

Comments

Title

Unique name identifying material model

Desc

Optional description of the material model

TITLE_OPTION

If selected material title option is used

MID

Material identification number (Integer > 0)

RO

Mass Density of the material

NPLOT

Plotting option

SPGRAV

Specific gravity of soil

RHOWAT

Density of water

VN, GAMMAR

Viscoplastic parameters

ITERMAX

Maximum number of plastic iterations

K

Bulk Modulus

G

Shear Modulus

PHIMAX

Peak Shear strength (friction) angle (degrees)

AHYP

Coefficient A for modified Drucker-Prager surface

COH

Cohesion shear strength at zero confinement (overburden)

ECCEN

Eccentricity parameter

AN

Strain hardening percent of PHIMAX where nonlinear effects start

ET

Strain hardening amount of nonlinear effects

230 Materials

Field

Comments

MCONT

Moisture content in soil

PWD1

Parameter for pore water effects on Bulk Modulus

PWSK

Skeleton Bulk Modulus

PWD2

Parameter for pore water effects on the effective pressure

PHIRES

Minimum internal frictional angle (radians)

DINT

Volumetric strain at initial threshold damage

VDFM

Void formation energy

DAMLEV

Level of damage that will cause element deletion

EPSMAX

Maximum principal failure strain

See Also: • LS-DYNA Keyword User’s Manual MAT_FHWA_SOIL_NEBRASKA Defines the material properties for a soil model with default property values for soils used at the University of Nebraska. Default units are in millimeter, milliseconds and kilograms.

Field

Comments

Title

Unique name identifying material model

Desc

Optional description of the material model

TITLE_OPTION

If selected material title option is used

MID

Material identification number (Integer > 0)

FCTIM

Factor to multiply milliseconds by to get desired time unit

FCTMAS

Factor to multiply Kg by to get desired mass unit

FCTLEN

Factor to multiply mm by to get desired length unit

See Also: • LS-DYNA Keyword User’s Manual

Materials 231 Materials

MAT_GAS_MIXTURE Defines the material properties for a material model that simulates gas mixture and works in conjunction with the multi-material ALE formulation.

Field

Comments

Title

Unique name identifying material model

Desc

Optional description of the material model

TITLE_OPTION

If selected material title option is used

MID

Material identification number (Integer > 0)

IADIAB

Flag for turning adiabatic compression logic ON/OFF 0 = ON ; 1 = OFF

RUNIV

Universal gas constant in per-mole unit

CVi

Heat Capacity at constant volume for upto eight different gases in per-mass unit gas (If RUNIV = 0 or blank)

MOLi

Molecular weight of each ideal gas in the mixture (mass-unit/molde) (if RUNIV is nonzero)

CPi

Heat Capacity at constant pressure for upto eight different gases in permass unit gas (If RUNIV = 0 or blank)

232 Materials

Field

Comments

Bi

First order coefficient for a temperature dependent heat capacity at constant pressure for up to eight different gases (If RUNIV = 0 or blank)

Ci

Second order coefficient for a temperature dependent heat capacity at constant pressure for up to eight different gases (If RUNIV = 0 or blank)

See Also: • LS-DYNA Keyword User’s Manual MAT_CFD Defines the material properties for a material model that allows constant, isotropic fluid properties to be defined for the incompressible/low-Mach CFD solver.

Field

Comments

Title

Unique name identifying material model

Desc

Optional description of the material model

TITLE_OPTION

If selected material title option is used

MID

Material identification number (Integer > 0)

RHO

Fluid Density

MU

Fluid Viscosity

K

Thermal Conductivity

CP

Heat Capacity

BETA

Coefficient of expansion

TREF

Reference Temperature

Materials 233 Materials

Field

Comments

GX, GY, GZ

Gravitational acceleration in the X, Y, Z direction

DIFFi

Diffusivity for Species i

See Also: • LS-DYNA Keyword User’s Manual MAT_CFD_CONSTANT Defines the material properties for a material model that allows constant, isotropic fluid properties to be defined for the incompressible/low-Mach CFD solver.

Field

Comments

Title

Unique name identifying material model

Desc

Optional description of the material model

TITLE_OPTION

If selected material title option is used

MID

Material identification number (Integer > 0)

RHO

Fluid Density

MU

Fluid Viscosity

K

Thermal Conductivity

CP

Heat Capacity

BETA

Coefficient of expansion

TREF

Reference Temperature

GX, GY, GZ

Gravitational acceleration in the X, Y, Z direction

DIFFi

Diffusivity for Species i

234 Materials

See Also: • LS-DYNA Keyword User’s Manual MAT_DESHPANDE_FLECK_FOAM Defines the material properties for aluminum foam, used as a filler material in aluminum extrusions to enhance the energy absorbing capability of the extrusion.

Field

Comments

Title

Unique name identifying material model

Desc

Optional description of the material model

TITLE_OPTION

If selected material title option is used

MID

Material identification number (Integer > 0)

RO

Mass Density of the material

E

Young’s Modulus

PR

Poisson’s Ratio

ALPHA

Parameter to Control Shape of yield surface

GAMMA, ALPHA2, BETA, SIGP

Equation parameters

EPSD

Densification strain

DERFI

Type of derivation in Material subroutine 0: Numerical 1: Analytical

CFAIL

Failure Strain

See Also: • LS-DYNA Keyword User’s Manual

Materials 235 Materials

MAT_COMPOSITE_MSC Defines the material properties for a material model to simulate the progressive failure analysis for composite materials consisting of unidirectional and woven fabric layers.

Field

Comments

Title

Unique name identifying material model

Desc

Optional description of the material model

TITLE_OPTION

If selected material title option is used

MID

Material identification number (Integer > 0)

RO

Mass Density of the material

EA

Young’s Modulus - longitudinal direction

EB

Young’s Modulus - transverse direction

EC

Young’s Modulus - through thickness direction

PRBA, PRCA, PRCB

Poisson’s Ratio in ba, ca, and cb directions

GAB, GBC, GCA

Shear Stress in ab bc, and ca directions

236 Materials

Field AOPT

Comments Material Axes option 0: Locally orthotropic with material axes determined by element nodes 1, 2, and 4. (Node 1 is the local origin, Node 2 is along the local a- axis; Local c-axis is the cross product of local a-axis, and the vector from node 1 to node 4; Local b- axis is the cross product of loca c- and a- axes.) 1: Locally orthotropic with material axis determined by a point in space, and the global location of the element center; this is the a- direction. This option is for solid elements only. 2: Globally orthotropic with material axis determined by3 vectors below.

MACF

Material Axes change flag: = 1 no change (default) = 2, switch material axes a and b = 3, switch material axes a and c = 4, switch material axes b and c

XP

X-coordinate of point p for AOPT=1

YP

Y-coordinate of point p for AOPT=1

ZP

Z-coordinate of point p for AOPT=1

Ai

Component of Vector a, for AOPT=2

Vi

Component of Vector v, for AOPT=3

Di

Component of Vector d, for AOPT=2

BETA

Layer in-plane rotational Angle (degrees)

SAT

Longitudinal Tensile Strength

SAC

Longitudinal Compressive Strength

SBT

Transverse Tensile Strength

SBC

Transverse Compressive Strength

SCT

Through thickness Tensile Strength

SFC

Crush Strength

SFS

Fiber mode shear strength

SAB, SBC, SCA

Matrix mode Shear Strength in ab bc, and ca planes

SFFC

Scale factor for residual compressive strength

Materials 237 Materials

Field AMODEL

Comments Material Model 1: Unidirectional layer model 2: Fabric layer model

PHIC

Coulomb friction angle

E_LIMT

Element eroding axial strain

S_DELM

Scale factor for delamination criteria

OMGMX

Limit damage parameter for elastic modulus

ECRSH

Limit compressive volume strain for element eroding

EEXPN

Limit tensile volume strain for element eroding

CERATE1

Coefficient for strain rate dependent strength properties

AM1

Coefficient for strain rate softening property for fiber in a direction

See Also: • LS-DYNA Keyword User’s Manual

238 Materials

MAT_COMPOSITE_MSC_DMG Defines the material properties for a material model to simulate the progressive failure analysis for composite materials consisting of unidirectional and woven fabric layers.

Field

Comments

Title

Unique name identifying material model

Desc

Optional description of the material model

TITLE_OPTION

If selected material title option is used

MID

Material identification number (Integer > 0)

RO

Mass Density of the material

EA

Young’s Modulus - longitudinal direction

EB

Young’s Modulus - transverse direction

EC

Young’s Modulus - through thickness direction

PRBA, PRCA, PRCB

Poisson’s Ratio in ba, ca, and cb directions

GAB, GBC, GCA

Shear Stress in ab bc, and ca directions

Materials 239 Materials

Field AOPT

Comments Material Axes option 0: Locally orthotropic with material axes determined by element nodes 1, 2, and 4. (Node 1 is the local origin, Node 2 is along the local a- axis; Local c-axis is the cross product of local a-axis, and the vector from node 1 to node 4; Local b- axis is the cross product of loca c- and a- axes.) 1: Locally orthotropic with material axis determined by a point in space, and the global location of the element center; this is the a- direction. This option is for solid elements only. 2: Globally orthotropic with material axis determined by3 vectors below.

MACF

Material Axes change flag: = 1 no change (default) = 2, switch material axes a and b = 3, switch material axes a and c = 4, switch material axes b and c

XP

X-coordinate of point p for AOPT=1

YP

Y-coordinate of point p for AOPT=1

ZP

Z-coordinate of point p for AOPT=1

Ai

Component of Vector a, for AOPT=2

Vi

Component of Vector v, for AOPT=3

Di

Component of Vector d, for AOPT=2

BETA

Layer in-plane rotational Angle (degrees)

SAT

Longitudinal Tensile Strength

SAC

Longitudinal Compressive Strength

SBT

Transverse Tensile Strength

SBC

Transverse Compressive Strength

SCT

Through thickness Tessile Strength

SFC

Crush Strength

SFS

Fiber mode shear strength

Sij

Transverse Shear Strength ij

SFFC

Scale factor for residual compressive strength

240 Materials

Field AMODEL

Comments Material Model 1: Unidirectional 2: Fabric

PHIC

Coulomb friction angle

E_LIMT

Element eroding axial strain

S_DELM

Scale factor for delamination criteria

OMGMX

Limit damage parameter for elastic modulus

ECRSH

Limit compressive volume strain

EEXPN

Limit tensile volume strain

CERATEi

Coefficient for strain rate dependent strength parameter, axial moduli, shear moduli, transverse moduli

See Also: • LS-DYNA Keyword User’s Manual MAT_MODIFIED_CRUSHABLE_FOAM Defines the material properties for a material model to simulate crushable foam with optional damping, tension cutoff and strain rate effects. Unloading is fully elastic. Tension is treated as elastic-perfectlyplastic at the tension cutoff value.

Field

Comments

Title

Unique name identifying material model

Desc

Optional description of the material model

TITLE_OPTION

If selected material title option is used

MID

Material identification number (Integer > 0)

RO

Mass Density of the material

Materials 241 Materials

Field

Comments

E

Young’s Modulus

PR

Poisson’s Ratio

TID

Load Curve Id defining Yield Stress vs. Volumetric Strain

TSC

Tensile Stress Cutoff

DAMP

Rate sensitivity via damping coefficient

NCYCLE

Number of cycles to determine volumetric strain rate

SRCLMT

Strain rate change limit

See Also: • LS-DYNA Keyword User’s Manual MAT_QUASILINEAR_VISCOELASTIC Defines the properties for a material model to simulate a quasi-linear, isotropic, viscoelastic material which represents biological soft tissue such as brain, kidney, etc.

Field

Comments

Title

Unique name identifying material model

Desc

Optional description of the material model

TITLE_OPTION

If selected material title option is used

MID

Material identification number (Integer > 0)

RO

Mass Density of the material

K

Bulk Modulus

LC1

Load Curve Id for the Relaxation function in shear

242 Materials

Field

Comments

LC2

Load Curve Id for the instantaneous Elastic response in shear

N

No. of Prony series terms in fit

GSTART

Starting value for least square fit

M

No. of terms used to determine the instantaneous elastic response

S0

Strain output option to be plotted as component 7 in LS-TAURUS 0: Maximum principal strain 1: Maximum Magnitude of principal strain 2: Maximum Effective strain

E_MIN

Minimum strain rate used to generate the load curve fron Ci

E_MAX

Maximum strain rate used to generate the load curve fron Ci

GAMA1, GAMA2

Material failure parameters

KF

Material failure parameter that controls the enclosed by the failure surface. .LE 0, ignore failure criterion. .GE. 0, use actual K value for failure criterion.

EH

Damage parameter

FORM

Formulation of Model. =0 original model by Fung which relaxes to a zero stress state as time approaches to infinity. = 1 Alternative model which relaxes to the quasistatice elastic response

C1 to C6

Coefficients of the instanteneous elastic response in compression and tension

See Also: • LS-DYNA Keyword User’s Manual

Materials 243 Materials

MAT_HILL_FOAM Defines the properties for a material model to simulate a highly compressible foam based on strain energy function, proposed by Hill. This model takes Poisson’s ratio effects into account.

Field

Comments

Title

Unique name identifying material model

Desc

Optional description of the material model

TITLE_OPTION

If selected material title option is used

MID

Material identification number (Integer > 0)

RO

Mass Density of the material

K

Bulk Modulus

N

Material constant

MU

Damping coefficient

LCID

Load Curve Id defining Force per unit area vs. Stretch Ratio

FITTYPE

Type of fit 1: Uniaxial 2: Biaxial

LCSR

Load Curve Id defining uniaxial (or biaxial, depending on FITTYPE) Stress ratio vs. Transverse Stretch Ratio

R

Mullinus effect model r coefficient

M

Mullinus effect model m coefficient

See Also: • LS-DYNA Keyword User’s Manual

244 Materials

MAT_VISCOELASTIC_HILL_FOAM Defines the properties for a material model to simulate a highly compressible foam based on strain energy function, proposed by Hill. with extensions to include large strain viscoelasticity proposed by Feng and Hallquist [2002].

Field

Comments

Title

Unique name identifying material model

Desc

Optional description of the material model

TITLE_OPTION

If selected material title option is used

MID

Material identification number (Integer > 0)

RO

Mass Density of the material

K

Bulk Modulus

N

Material constant

MU

Damping coefficient

LCID

Load Curve Id defining Force per unit area vs. Stretch Ratio

FITTYPE

Type of fit 1: Uniaxial 2: Biaxial

LCSR

Load Curve Id defining uniaxial (or biaxial, depending on FITTYPE) Stress ratio vs. Transverse Stretch Ratio

LCVE

Load Curve Id defining the Relaxation function in shear

NT

No. of Prony series terms in fit

GSTART

Starting value for least square fit

See Also: • LS-DYNA Keyword User’s Manual

Materials 245 Materials

MAT_LOW_DENSITY_SYNTHETIC_FOAM Defines the properties of rate independent low density foams exhibiting considerably reduced properties in the loading-unloading curve after the first loading cycle.

Field

Comments

Title

Unique name identifying material model

Desc

Optional description of the material model

TITLE_OPTION

If selected material title option is used

MID

Material identification number (Integer > 0)

RO

Mass Density of the material

E

Young’s Modulus

LCID1

Load Curve Id defining nominal Stress vs. Strain for the first loading cycle

LCID2

Load Curve Id defining nominal Stress vs. Strain for loading cycles after the first loading cycle is completed

HU

Hysteric unloading factor between 0 and 1

BETA

Decay constant to model creep in unloading

DAMP

Viscous coefficient

SHAPE

Shape factor for unloading

FAIL

Failure option after cutoff stress 0: Tensile Stress remains at cutoff 1: Tensile Stress resets to zero

246 Materials

Field BVFLAG

Comments Bulk viscosity activation flag 0: No 1: Active

ED

Optional Young’s relaxation modulus for rate effects

BETA1

Optional decay constant

KCON

Stiffness coefficient for contact interface stiffness

REF

Use reference geometry to initialize stress tensor 0: Off 1: On

TC

Tension Cutoff Stress

RFLAG

Rate type for input: = 0, LCID1 and LCID2 should be input as functions of true strain rate = 1, LCID1 and LCID2 should be functions of engineering strain rate

DIRT

Strain rate averaging flag: = 0, use weighted running average .LE. 0, average the last eleven values .GT. 0, average over the last DIRT time units

K GAMA1, GAMA2

Material failure parameters

EH

Damage parameter

See Also: • LS-DYNA Keyword User’s Manual MAT_LOW_DENSITY_SYNTHETIC_FOAM_ORTHO Defines the properties of rate independent low density foams exhibiting considerably reduced properties in the loading-unloading curve after the first loading cycle. This material model considers any orthotropic behavior after the first loading and unloading cycle of the material in the orthogonal directions.

Materials 247 Materials

Field

Comments

Title

Unique name identifying material model

Desc

Optional description of the material model

TITLE_OPTION

If selected material title option is used

MID

Material identification number (Integer > 0)

RO

Mass Density of the material

E

Young’s Modulus

LCID1

Load Curve Id defining nominal Stress vs. Strain for the first loading cycle

LCID2

Load Curve Id defining nominal Stress vs. Strain for loading cycles after the first loading cycle is completed

HU

Hysteric unloading factor between 0 and 1

BETA

Decay constant to model creep in unloading

DAMP

Viscous coefficient

SHAPE

Shape factor for unloading

FAIL

Failure option after cutoff stress 0: Tensile Stress remains at cutoff 1: Tensile Stress resets to zero

248 Materials

Field BVFLAG

Comments Bulk viscosity activation flag 0: No 1: Active

ED

Optional Young’s relaxation modulus for rate effects

BETA1

Optional decay constant

KCON

Stiffness coefficient for contact interface stiffness

REF

Use reference geometry to initialize stress tensor 0: Off 1: On

TC

Tension Cutoff Stress

RFLAG

Rate type for input: = 0, LCID1 and LCID2 should be input as functions of true strain rate = 1, LCID1 and LCID2 should be functions of engineering strain rate

DIRT

Strain rate averaging flag: = 0, use weighted running average .LE. 0, average the last eleven values .GT. 0, average over the last DIRT time units

K GAMA1, GAMA2

Material failure parameters

EH

Damage parameter

See Also: • LS-DYNA Keyword User’s Manual

Materials 249 Materials

MAT_SIMPLIFIED_RUBBER/FOAM Defines the properties of a rubber amd foam model defined by a single uniaxial load curve or by a family of curves at discrete strain rates.

Field

Comments

Title

Unique name identifying material model

Desc

Optional description of the material model

TITLE_OPTION

If selected material title option is used

MID

Material identification number (Integer > 0)

RO

Mass Density of the material

KM

Linear Bulk Modulus

MU

Damping coefficient

G

Shear Modulus

SIGF

Limit stress for frequency independent, frictional, damping

REF

Use Reference Geometry (defined in *INITIAL_FOAM_REFERENCE_GEOMETRY) to initialize the stress tensor. 0 = ON ; 1 = OFF

PRTEN

Tensile Poisson’s ratio. = 0 indicates that PR/BETA will serve as Poisoon’s ratio for both tension and compression in shells. Otherwise, PR/BETA will serve as Poisoon’s ratio for compression in shells.

SGL

Specimen Gauge Length

SW

Specimen Width

ST

Specimen Thickness

250 Materials

Field

Comments

LCID

Load Curve Id defining Force vs. Actual change in gauge length

TENSION

Parameter to control rate effect -1: Rate effects are treated for loading either in tension or in compression (but not for unloading) 0: Rate effects are treated for loading compressive loading only 1:Rate effects are treated identically for tension and compressive loading only

RTYPE

Strain rate type 0: True 1: Engineering

AVGOPT

Averaging option to determine strain rate (to reduce numerical noise) 0: Simple average of twelve time steps 1: Running 12-point average

PR/BETA

If value is between 0.0 and 0.5 (exclusive), the value give here is taken as Poisson’s ratio. If value is exactly 0.0 (zero), an incompressible rubber like behavior is assumed, and a value of 0.495 is used inside the software. If zero Poisson’s ratio is desired, use a small value such as 0.001 for PR.

K

Material failure parameter that controls the enclosed by the failure surface. .LE 0, ignore failure criterion. .GE. 0, use actual K value for failure criterion.

GAMA1, GAMA2

Material failure parameters

EH

Damage parameter

See Also: • LS-DYNA Keyword User’s Manual

Materials 251 Materials

MAT_SEISMIC_BEAM Defines the properties of a material characterized by lumped plasticity to be developed at the ‘node 2’ end of Belytschko-Schwer beams. The plastic yield surface allows interaction between the two moments and the axial force.

Field

Comments

Title

Unique name identifying material model

Desc

Optional description of the material model

TITLE_OPTION

If selected material title option is used

MID

Material identification number (Integer > 0)

RO

Mass Density of the material

E

Young’s Modulus

PR

Poisson’s Ratio

AOPT

Axial force option 0: Axial Load Curves are Collapse Load vs. Strain NE. 0: Axial Load Curves are Collapse Load vs. Change in Length

252 Materials

Field FTYPE

Comments Formulation type for interaction 1: Parabolic coefficients 2: Japanese Code, axial force and major axis bending

DEGRADE

Flag for degrading moment behavior 0 = behavior as in previous versions 1 = Fatigue-type moment-rotation behavior 2 = FEMA-type moment-rotation behavior

IFEMA

Flag for input of FEMA thresholds = 0 No inputs ; 1 = Input of rotation thresholds only =2 Input of rotation and axial strain thresholds

LCPMS

Load Curve Id for Plastic Moment vs. Rotation about s at node 2

SFS

Scale factor on s -moment at node 2

LCPMT

Load Curve Id for Plastic Moment vs. Rotation about t at node 2

SFT

Scale factor on t -moment at node 2

LCAT

Load Curve Id for axial tensile yield force vs. total tensile strain (or elongation, see AOPT option)

SFAT

Scale factor for axial tensile force

LCAC

Load Curve Id for axial compressive force vs. strain/elongation

SFAC

Scale factor for axial compressive force

ALPHA, BETA, Parameters to define yield surface GAMMA, DELTA, A, B FOFFS

Force offset for Yield Surface

SIGY

Yield Stress

D

Depth of section used for interaction curve

W

Width of section used for interaction curve

TF

Flange Thickness of section used for interaction curve

TW

Web Thickness of section used for interaction curve

PR1 - PR4

Plastic rotation thresholds 1 to 4

TS1 - TS4

Tensile axial strain hresholds 1 to 4

CS1 - CS4

Compressive axial strain hresholds 1 to 4

Materials 253 Materials

See Also: • LS-DYNA Keyword User’s Manual MAT_SOIL_BRICK Defines the properties of clay like soils accurately.

Field

Comments

Title

Unique name identifying material model

Desc

Optional description of the material model

TITLE_OPTION

If selected material title option is used

MID

Material identification number (Integer > 0)

RO

Mass Density of the material

RLAMDA, RKAPPA, RIOTA, RBETAi

Material coefficient

RMU

Shape factor coefficient

RNU

Poisson’s ratio

RLCID

Load Curve Id referring to a curve defining up to ten pairs of ‘string-length’ vs. G/Gmax points.up to 10 points of string-length vs. Gmax

TOL

User defined tolerance for convergence checking

PGCL

Pre consolidation ground level

SUB-INC

User defined strain increment size

BLK

Elastic bulk stiffness of the soil

GRAV

Gravitational acceleration

254 Materials

Field THEORY

Comments Version of material subroutine used 0 (default) = 1995 version (vectorized) ; 4 = 1995 version (unvectorized)

RVHNH

Anisotropy parameter

XSICRIT, ALPHA

Anisotropy parameters

RVH

Anisotropy ratio (Ev/Eh)

RNU21

Anisotropy ratio (ν2/ν1)

ANISO_4

Anisotropy parameter

See Also: • LS-DYNA Keyword User’s Manual MAT_DRUCKER_PRAGER Defines the properties of materials such as soils modeled with the modified Drucker-Prager yield surface.

Field

Comments

Title

Unique name identifying material model

Desc

Optional description of the material model

TITLE_OPTION

If selected material title option is used

MID

Material identification number (Integer > 0)

RO

Mass Density of the material

GMOD

Elastic Shear Modulus

RNU

Poisson’s ratio

RKF

Failure surface shape parameter

Materials 255 Materials

Field

Comments

PHI

Angle of friction (radians)

CVAL

Cohesive Value

PSI

Dilation angle (radians)

STR_LIM

Factor for calculating minimum shear strength of material which is calculated as STR_LIM*CVAL

GMODDP

Depth at which shear modulus is correct

PHIDP

Depth at which friction angle is correct

CVALDP

Depth at which cohesive value is correct

PSIDP

Depth at which dilation angle is correct

GMODGR

Gradient at which shear modulus increases with depth

PHIGR

Gradient at which friction angle increases with depth

CVALGR

Gradient at which cohesive value increases with depth

PSIGR

Gradient at which dilation angle increases with depth

See Also: • LS-DYNA Keyword User’s Manual

256 Materials

MAT_RC_SHEAR_WALL Defines the properties of materials to model cyclic shear loading of reinforced concrete walls (available only for shell elements).

Field

Comments

Title

Unique name identifying material model

Desc

Optional description of the material model

TITLE_OPTION

If selected material title option is used

MID

Material identification number (Integer > 0)

RO

Mass Density of the material

E

Young’s Modulus

PR

Poisson’s Ratio

TMAX

Ultimate shear stress

Materials 257 Materials

Field

Comments

Fc

Unconfirmed compressive strength of Concrete

PREF

Percent reinforcement

FYIELD

Yield stress of reinforcement

SIG0

Overburden stress

UNCONV

Unit conversion factor, to compute ultimate tensile stress of Concrete

ALPHA

Shear span factor

FT

Cracking stress in direct tension

ERIENF

Young’s Modulus for reinforcement

A, B, C, D, E

Hysteresis constants to determine shape of the hysteresis loops

F

Strength gradient factor

Yi

Shear strain points on stress vs. strain curve

Ti

Shear stress points on stress vs. strain curve

AOPT

Material Axes option 0: Locally orthotropic with material axes determined by element nodes 1, 2, and 4. (Node 1 is the local origin, Node 2 is along the local a- axis; Local c-axis is the cross product of local a-axis, and the vector from node 1 to node 4; Local b- axis is the cross product of loca c- and a- axes.) 1: Locally orthotropic with material axis determined by a point in space, and the global location of the element center; this is the a- direction. This option is for solid elements only. 2: Globally orthotropic with material axis determined by3 vectors below.

XP

X-coordinate of point p for AOPT=1

YP

Y-coordinate of point p for AOPT=1

ZP

Z-coordinate of point p for AOPT=1

Ai

Component of Vector a, for AOPT=2

Vi

Component of Vector v, for AOPT=3

Di

Component of Vector d, for AOPT=2

BETA

Layer in-plane rotational Angle

See Also: • LS-DYNA Keyword User’s Manual

258 Materials

MAT_CONCRETE_BEAM Defines an elasto-plastic material with an arbitrary stress-strain curve and arbitrary strain rate dependency. Also, failure based on plastic strain or a minimum time step can be defined.

Field

Comments

Title

Unique name identifying material model

Desc

Optional description of the material model

TITLE_OPTION

If selected material title option is used

MID

Material identification number (Integer > 0)

RO

Mass Density of the material

E

Young’s Modulus

PR

Poisson’s Ratio

SIGY

Yield Stress

ETAN

Tangent Modulus

C, P

Strain Rate Parameters

FAIL

Failure Flag

TDEL

Minimum time step size for automatic element deletion

LCSS

Load Curve Id defining Effective Stress vs. Effective Plastic Strain in compression

LCSR

Load Curve Id defining Strain rate effects on Yield Stress

Materials 259 Materials

Field NOTEN

Comments No-tension flag 0: Takes tension 1: Does not take Tension 2: Takes tension upto value given by TENCUT (Tension cutoff)

TENCUT

Tension cutoff stress

SDR

Stiffness degradation factor

See Also: • LS-DYNA Keyword User’s Manual MAT_GENERAL_SPRING_DISCRETE_BEAM Defines the properties of materials with elastic and elastoplastic springs with damping to be represented by discrete beam elements using six springs, each acting along one of the six local degrees-of-freedom.

260 Materials

For elastic behavior, use a load curve of yield force or moment versus displacement or rotation. For inelastic case, use a load curve of yield force or moment versus plastic deflection or rotation.

Materials 261 Materials

262 Materials

Field

Comments

Title

Unique name identifying material model

Desc

Optional description of the material model

TITLE_OPTION

If selected material title option is used

MID

Material identification number (Integer > 0)

RO

Mass Density of the material

DOFi

Active degree-of-freedom

TYPEi

Behavior 0: Elastic 1: Inelastic

Ki

Elastic loading/unloading stiffness

Di

Optional viscous damping coefficient

CDFi

Compressive displacement at failure

TDFi

Tensile displacement at failure

FLCIDi

Load Curve Id defining Force (or Moment) vs. Displacement for nonlinear elastic (TYPE1 = 0). For inelastic behavior, this curve defines the yield force vs. plastic deflection.

HLCIDi

Load Curve Id defining Force vs. Relative Velocity

C1_i, C2_i

Damping coefficients

DLEi

Scale factor for time unit

GLCIDi

Load Curve Id defining scale factor vs. deflection for HLCIDi

See Also: • LS-DYNA Keyword User’s Manual

Materials 263 Materials

MAT_SEISMIC_ISOLATOR Defines the properties of materials used as sliding and elastometric seismic isolation bearings. This material model uses a bi-directional coupled plasticity theory (available only for discrete beam elements).

Field

Comments

Title

Unique name identifying material model

Desc

Optional description of the material model

TITLE_OPTION

If selected material title option is used

MID

Material identification number (Integer > 0)

RO

Mass Density of the material

A, GAMMA, BETA

Non dimensional variable

DISPY

Yield displacement

STIFFV

Vertical stiffness

ITYPE

Type 0: Sliding 1: Elastomeric

PRELOAD

Vertical preload

DAMP

Damping ratio

MXi

Moment factor at end i in local x direction

MYi

Moment factor at end i in local y direction

FMAX

Maximum dynamic friction coefficient

264 Materials

Field

Comments

DELF

Difference between maximum and Static Friction coefficient

AFRIC

Velocity multiplier in sliding friction equation

RADX

Radius for sliding in local x direction

RADY

Radius for sliding in local y direction

RADB

Radius of retaining ring

STIFFL

Stiffness for lateral contact against retaining ring

STIFFTS

Stiffness for tensile vertical response (sliding)

FORCEY

Yield force

ALPHA

Ratio of post and pre yielding stiffness

STIFFT

Stiffness for tensile vertical response (elastomeric)

DFAIL

Lateral displacement at which isolator fails

FMAXYC

Maximum dynamic friction coefficient in compression in local y-direction

FMAXXT

Maximum dynamic friction coefficient in tension in local x-direction

FMAXYT

Maximum dynamic friction coefficient in tension in local y-direction

YLOCK

Stiffness locking the local y- displacement (optional in single axis sliding)

See Also: • LS-DYNA Keyword User’s Manual

Materials 265 Materials

MAT_JOINTED_ROCK Defines the properties of jointed rocks.

Field

Comments

Title

Unique name identifying material model

Desc

Optional description of the material model

TITLE_OPTION

If selected material title option is used

MID

Material identification number (Integer > 0)

RO

Mass Density of the material

GMOD

Elastic Shear Modulus

RNU

Poisson’s ratio

RKF

Failure surface shape parameter

PHI

Angle of friction (radians)

CVAL

Cohesive Value

PSI

Dilation angle (radians)

STR_LIM

Factor for calculating minimum shear strength of material which is calculated as STR_LIM*CVAL

NPLANES

No of joint planes

266 Materials

Field ELASTIC

Comments Flag for Elastic Behavior 0: Non elastic 1: Elastic

LCCPDR

Load Curve Id for extra cohesion for parent material (dynamic relaxation)

LCCPT

Load Curve Id for extra cohesion for parent material (transient)

LCCJDR

Load Curve Id for extra cohesion for joints (dynamic relaxation)

LCCJT

Load Curve Id for extra cohesion for joint material (transient)

LCSFAC

Load Curve Id giving factor on Strength vs. Time

GMODDP

Depth at which shear modulus is correct

PHIDP

Depth at which friction angle is correct

CVALDP

Depth at which cohesive value is correct

PSIDP

Depth at which dilation angle is correct

GMODGR

Gradient at which shear modulus increases with depth

PHIGR

Gradient at which friction angle increases with depth

CVALGR

Gradient at which cohesive value increases with depth

PSIGR

Gradient at which dilation angle increases with depth

DIPi

Angle (degrees) of plane below the horizontal

STRIKEi

Plan view angle (degrees) of downhill vector drawn on the plane

CPLANEi

Cohesion for shear behavior on plane i

FRPLANEi

Friction angle for shear behavior on plane i

TPLANEi

Tensile strength across plane i

SHRMAXi

Maximum shear stress on plane i

LOCALi

DIP and STRIKE Coordinate System flag 0: with respect to Global axes 1: with respect to element local axes

See Also: • LS-DYNA Keyword User’s Manual

Materials 267 Materials

MAT_SPRING_ELASTIC Defines the properties of a translational or rotational elastic spring placed between two nodes. Only one degree of freedom is connected.

Field

Comments

Title

Unique name identifying material model

Desc

Optional description of the material model

TITLE_OPTION

If selected material title option is used

MID

Material identification number (Integer > 0)

K

Elastic Stiffness (Translational or Rotational)

See Also: • LS-DYNA Keyword User’s Manual MAT_DAMPER_VISCOUS Defines the properties of translational and rotational dampers located between two nodes. Only one degree of freedom is connected.

Field

Comments

Title

Unique name identifying material model

Desc

Optional description of the material model

TITLE_OPTION

If selected material title option is used

MID

Material identification number (Integer > 0)

DC

Damping Constant (Force/Displacement rate or Moment/Rotation rate)

268 Materials

See Also: • LS-DYNA Keyword User’s Manual MAT_SPRING_ELASTOPLASTIC Defines the properties of discrete springs providing an elastoplastic translational or rotational spring with isotropic hardening located between two nodes. Only one degree of freedom is connected.

Field

Comments

Title

Unique name identifying material model

Desc

Optional description of the material model

TITLE_OPTION

If selected material title option is used

MID

Material identification number (Integer > 0)

K

Elastic Stiffness (Translational or Rotational)

KT

Tangent Stiffness

FY

Yield Force or Moment

See Also: • LS-DYNA Keyword User’s Manual

Materials 269 Materials

MAT_SPRING_NONLINEAR_ELASTIC Defines the properties of discrete springs providing a nonlinear elastic translational or rotational spring with arbitrary force versus displacement and moment versus rotation data. Only one degree of freedom is connected.

Field

Comments

Title

Unique name identifying material model

Desc

Optional description of the material model

TITLE_OPTION

If selected material title option is used

MID

Material identification number (Integer > 0)

LCD

Load Curve Id defining Force vs. Displacement or Moment vs. Rotation

LCR

Load Curve Id defining Scale factor on Force or Moment as a function of relative velocity, or rotational velocity respectively

See Also: • LS-DYNA Keyword User’s Manual

270 Materials

MAT_DAMPER_NONLINEAR_VISCOUS Defines the properties of discrete dampers providing a viscous translational or rotational damper with arbitrary force versus velocity or a moment versus rotational velocity data. Only one degree of freedom is connected.

Field

Comments

Title

Unique name identifying material model

Desc

Optional description of the material model

TITLE_OPTION

If selected material title option is used

MID

Material identification number (Integer > 0)

LCDR

Load Curve Id defining the Force vs. rate of Displacement or Moment vs. rate of Rotation relationship

See Also: • LS-DYNA Keyword User’s Manual MAT_SPRING_GENERAL_NONLINEAR Defines the properties of discrete springs providing a general nonlinear translational or rotational spring with arbitrary loading and unloading data. It also considers hardening or softening. Only one degree of freedom is connected.

Field

Comments

Title

Unique name identifying material model

Desc

Optional description of the material model

TITLE_OPTION

If selected material title option is used

Materials 271 Materials

Field

Comments

MID

Material identification number (Integer > 0)

LCDL

Loading Curve Id for Force vs. Displacement or Moment vs. Rotation

LCDU

Unloading Load Curve Id for Force vs. Displacement or Moment vs. Rotation

BETA

Hardening parameter

TYI

Initial Yield force in tension

CYI

Initial Yield force in compression

See Also: • LS-DYNA Keyword User’s Manual MAT_SPRING_MAXWELL Defines the properties of discrete springs providing a three Parameter Maxwell Viscoelastic translational or rotational spring. Only one degree of freedom is connected.

Field

Comments

Title

Unique name identifying material model

Desc

Optional description of the material model

TITLE_OPTION

If selected material title option is used

MID

Material identification number (Integer > 0)

K0

Short term stiffness

KI

Long term stiffness

BETA

Decay constant

TC

Cutoff time. After this time a constant force/moment transmitted

272 Materials

Field

Comments

FC

Force/Moment after cutoff time

COPT

Time implementation option 0: Incremental time change 1: Continuous time change

See Also: • LS-DYNA Keyword User’s Manual MAT_SPRING_INELASTIC Defines the properties of discrete springs and dampers providing an inelastic tension or compression only, translational or rotational spring.

Field

Comments

Title

Unique name identifying material model

Desc

Optional description of the material model

TITLE_OPTION

If selected material title option is used

MID

Material identification number (Integer > 0)

LCFD

Load Curve Id defining the Force/Torque vs. Displacement/Twist relationship

KU

Unloading Stiffness

CTF

Flag for compression/tension -1: Tension only 1: Compression only (Default CTF value is 0, which is same as 1)

See Also: • LS-DYNA Keyword User’s Manual

Materials 273 Materials

MAT_SPRING_TRILINEAR_DEGRADING Defines the properties of concrete shear walls under seismic loading modelled as discrete elements. It represents cracking of the concrete, yield of the reinforcement, and overall failure.

Field

Comments

Title

Unique name identifying material model

Desc

Optional description of the material model

TITLE_OPTION

If selected material title option is used

MID

Material identification number (Integer > 0)

DEFL1

Deflection at point where concrete cracks

F1

Force corresponding to DEFL1

DEFL2

Deflection at reinforcement yield

F2

Force corresponding to DEFL2

DEFL3

Deflection at complete failure

F3

Force corresponding to DEFL3

FFLAG

Failure Flag

See Also: • LS-DYNA Keyword User’s Manual

274 Materials

MAT_SPRING_SQUAT_SHEARWALL Defines the properties of squat shear walls modelled as discrete elements. This material model allows concrete cracking, reinforcement yield, and ultimate strength, followed by degradation of strength, leading finally to collapse.

Field

Comments

Title

Unique name identifying material model

Desc

Optional description of the material model

TITLE_OPTION

If selected material title option is used

MID

Material identification number (Integer > 0)

A14, B14, C14, D14, E14

Material coefficient

LCID

Load Curve Id referencing the maximum strength envelope curve

FSD

Sustained strength reduction factor

See Also: • LS-DYNA Keyword User’s Manual

Materials 275 Materials

MAT_SPRING_MUSCLE Defines the properties for discrete springs and dampers. This is a Hill-type muscle model with activation.

Field

Comments

Title

Unique name identifying material model

Desc

Optional description of the material model

TITLE_OPTION

If selected material title option is used

MID

Material identification number (Integer > 0)

L0

Initial muscle length

VMAX

Maximum CE shortening velocity

SV

Scale factor for Vmax vs. Active State

A

Scale factor for Activation Level vs. Time function

FMAX

Peak isometric force

TL

Scale factor for Active tension vs. length function

TV

Scale factor for Active tension vs. velocity function

FPE

Scale factor for Force vs. length function, for parallel elastic element

LMAX

Relative length at FPE=FMAX

KSH

Constant governing the exponential rise of FPE

LCID_SV

Load Curve Id defining Vmax vs. active state

LCID_A

Load Curve Id defining Active level vs. Time function

LCID_TL

Load Curve Id defining Active tension vs. Length function

LCID_TV

Load Curve Id defining Active tension vs. velocity function

LCID_FPE

Load Curve Id defining Force vs. Length function

See Also: • LS-DYNA Keyword User’s Manual

276 Materials

MAT_THERMAL_ISOTROPIC Defines isotropic thermal properties of materials in coupled structural/thermal and thermal only analyses.

Field

Comments

Title

Unique name identifying material model

Desc

Optional description of the material model

TITLE_OPTION

If selected material title option is used

MID

Material identification number (Integer > 0)

TRO

Thermal Density

TGRLC

Thermal generation rate value

TGMULT

Thermal generation rate multiplier

TLAT

Phase chnage temperature

HLAT

Latent heat

HC

Heat capacity

TC

Thermal conductivity

See Also: • LS-DYNA Keyword User’s Manual MAT_THERMAL_ORTHOTROPIC Defines orthotropic thermal properties in coupled structural/thermal and thermal only analyses.

Materials 277 Materials

Field

Comments

Title

Unique name identifying material model

Desc

Optional description of the material model

TITLE_OPTION

If selected material title option is used

MID

Material identification number (Integer > 0)

TRO

Thermal Density

TGRLC

Thermal generation rate value

TGMULT

Thermal generation rate multiplier

AOPT

Material Axes option 0: Locally orthotropic with material axes determined by element nodes 1, 2, and 4. (Node 1 is the local origin, Node 2 is along the local a- axis; Local c-axis is the cross product of local a-axis, and the vector from node 1 to node 4; Local b- axis is the cross product of loca c- and a- axes.) 1: Locally orthotropic with material axis determined by a point in space, and the global location of the element center; this is the a- direction. This option is for solid elements only. 2: Globally orthotropic with material axis determined by3 vectors below.

TLAT

Phase chnage temperature

HLAT

Latent heat

278 Materials

Field

Comments

K1, K2, K3

Thermal conductivity in local x, y and z, respectively

XP

X-coordinate of point p for AOPT=1

YP

Y-coordinate of point p for AOPT=1

ZP

Z-coordinate of point p for AOPT=1

Ai

Component of Vector a, for AOPT=2

Di

Component of Vector d, for AOPT=2

See Also: • LS-DYNA Keyword User’s Manual MAT_THERMAL_ISOTROPIC_TD Defines temperature dependent isotropic thermal properties in coupled structural/thermal and thermal only analyses.

Field

Comments

Title

Unique name identifying material model

Desc

Optional description of the material model

TITLE_OPTION

If selected material title option is used

MID

Material identification number (Integer > 0)

TRO

Thermal Density

TGRLC

Thermal generation rate value

Materials 279 Materials

Field

Comments

TGMULT

Thermal generation rate multiplier

TLAT

Phase chnage temperature

HLAT

Latent heat

LC_C

Load Curve defining Heat capacity (C) Vs. Temperature

LC_K

Load Curve defining Thermal Conductivity (K) Vs. Temperature

See Also: • LS-DYNA Keyword User’s Manual MAT_ORTHOTROPIC_TD Defines temperature dependent orthotropic thermal properties in coupled structural/thermal and thermal only analyses.

280 Materials

Field

Comments

Title

Unique name identifying material model

Desc

Optional description of the material model

TITLE_OPTION

If selected material title option is used

MID

Material identification number (Integer > 0)

TRO

Thermal Density

TGRLC

Thermal generation rate value

TGMULT

Thermal generation rate multiplier

AOPT

Material Axes option 0: Locally orthotropic with material axes determined by element nodes 1, 2, and 4. (Node 1 is the local origin, Node 2 is along the local a- axis; Local c-axis is the cross product of local a-axis, and the vector from node 1 to node 4; Local b- axis is the cross product of loca c- and a- axes.) 1: Locally orthotropic with material axis determined by a point in space, and the global location of the element center; this is the a- direction. This option is for solid elements only. 2: Globally orthotropic with material axis determined by vectors below.

LC_C

Load Curve defining Heat capacity Vs. Time

LC_KX

Load Curve defining Thermal conductivity in local X Vs. Time

LC_KY

Load Curve defining Thermal conductivity in local Y Vs. Time

LC_KZ

Load Curve defining Thermal conductivity in local Z Vs. Time

XP

X-coordinate of point p for AOPT=1

YP

Y-coordinate of point p for AOPT=1

ZP

Z-coordinate of point p for AOPT=1

Ai

Component of Vector a, for AOPT=2

Di

Component of Vector d, for AOPT=2

See Also: • LS-DYNA Keyword User’s Manual

Materials 281 Materials

MAT_THERMAL_ISOTROPIC_PHASE_CHANGE Defines temperature dependent isotropic properties with phase changes in coupled structural/thermal and thermal only analyses.

Field

Comments

Title

Unique name identifying material model

Desc

Optional description of the material model

TITLE_OPTION

If selected material title option is used

MID

Material identification number (Integer > 0)

TRO

Thermal Density

TGRLC

Thermal generation rate value

TGMULT

Thermal generation rate multiplier

LC_C

Load Curve defining Heat capacity Vs. Temperature

LC_K

Load Curve defining Thermal conductivity Vs. Temperature

SOLT

Solid Temperature

LIQT

Liquid Temperature

LH

Latent Heat

282 Materials

See Also: • LS-DYNA Keyword User’s Manual MAT_THERMAL_ISOTROPIC_TD_LC Defines temperature dependent isotropic thermal properties by specifying a load curve in coupled structural/thermal and thermal only analyses.

Field

Comments

Title

Unique name identifying material model

Desc

Optional description of the material model

TITLE_OPTION

If selected material title option is used

MID

Material identification number (Integer > 0)

TRO

Thermal Density

TGRLC

Thermal generation rate value

TGMULT

Thermal generation rate multiplier

HCLC

Load Curve Id specifying Heat capacity vs. Temperature

TCLC

Load Curve Id specifying Thermal conductivity vs. Temperature

TGRLCID

Load Curve Id specifying Thermal generation rate curve number

See Also: • LS-DYNA Keyword User’s Manual

Properties 273

Properties

274 Properties

Properties Overview Typical properties include cross-sectional properties of beam elements, thicknesses of plate and shell elements, element integration rules, and hourglass controls. Properties are assigned to the elements of a specified part or element type, either directly to the elements, or indirectly through the part to which the elements belong.

Element Types and Associated Properties Thin Shell Elements Two-dimensional elements, commonly referred to as plate and shell elements, are used to represent areas in your model where one of the dimensions is small in comparison to the other two. As shown Figure 1 the thickness is substantially less than dimensions a or b.

Figure 1

Typical Plate Element

ELEMENT_SHELL - General-purpose plate elements (4-noded) capable of carrying in plane force, bending forces, and transverse shear force. The triangular element is defined by repeating the third for the fourth node. This family of elements are the most commonly used shell elements in the SimXpert crash element library. These are the element types generated by the Automesher.

Properties 275 Properties

*SECTION_SHELL - The thin shell elements are commonly referred to as the plate and shell elements within SimXpert. Their properties, are defined using the *SECTION_SHELL entry. The format of the *SECTION_SHELL entry is as follows:

276 Properties

Field

Contents

SECID

Section ID, to be referred by parts

ELFORM

Element formulation options = 1: Hughes-Liu = 2: Belytscho-Tsay = 3: BCIZ triangular shell = 4: C0 triangular shell = 5: Belytscho-Tsay membrane = 6: S/R Hughes-Liu = 8: Belytscho-Leviathan shell = 9: Fully integrated Belytscho-Tsay membrane = 10: Belytscho-Wong-Chiang = 11: Plane stress (x-y plane) = 12: Fast (co-rotational) Hughes-Liu = 13: Plane strain (x-y plane) = 14: Axisymmetric solid (y-axis of symmetry) - area weighted = 15: Axisymmetric solid (y-axis of symmetry) - volume weighted = 16: Fully integrated shell element = 17: Fully integrated DKT triangular shell element = 18: Fully integrated DK quadrilateral/triangular shell element = 20: Fully integrated linear assumed strain C0 shell = 21: Fully integrated linear assumed strain (5 DOF per node) C0 shell = 22: Linear shear panel element (3 DOF per node)

SHRF

Shear correction factor (value of 5/6 is recommended for solid plate)

NIP

Number of through thickness integration points

Properties 277 Properties

Field PROPT

Contents Printout options = 0: Average resultants and fiber lengths = 1: resultants at plan points and fiber lengths = 3: Resultants, stresses at all points, fiber lengths

QR

Quadrature rule LT 0.: Absolute value is used as the Quadrature rule EQ. 0.: Gauss Rule (up to five points permitted) EQ. 1.: Trapezoidal Rule

ICOMP

Flag for orthotropic/anisotropic layered composite material model = 0: Homogeneous =1: Composite

SETYP

2D solid element type (defined for ELFORM 13, 14, and 15) = 1: Lagrangian = 2: Eulerian (single material with voids) = 3: ALE

T1

Shell thickness at node 1

T2, T3, T4

Shell thickness at nodes 2, 3, and 4 respectively

NLOC

Location of reference surface normal to s axis (Hughes-Liu elements: ELFORM = 1 or 6)

MAREA

Nonstructural mass per unit area

IDOF

Applies to shell element types 25 and 26. .EQ. 1(default): The thickness field is continuous across the element edges for metal-forming applications. .EQ. 2: The thickness field is discontinuous across the element edges. This is necessary for applications such as crashworthiness where shell intersections, sharp included angles, and non-smooth deformations exist.

EDGSET

Edge node set, required for shell type seatbelts.

AFAC

Smoothing weight factor - simple average (No smoothing if value is -1.)

BFAC

Smoothing weight factor - volume weighting

278 Properties

Field

Contents

CFAC

Smoothing weight factor - isoparametric

DFAC

Smoothing weight factor - equipotential

EFAC

Smoothing weight factor - equilibrium

START

Start time for smoothing

END

End time for smoothing

AAFAC

ALE advection factor

DX, DY

Normalized dilatation parameters of the kernel function in X and Y directions respectively

ISPLINE

Replaces choice for the EFG kernel functions definition in *CONTROL_EFG.

IDILA

Replaces choice for the normalized dilation parameter definition in *CONTROL_EFG.

IRID

Integration Rule Id (User defined)

The element coordinate systems for the shell element is shown in Figure 2. The orientation of the element coordinate system is determined by the order of the connectivity for the nodes. The element z-axis, often referred to as the positive normal, is determined using the right-hand rule. Therefore, if you change the order of the nodal connectivity, the direction of this positive normal also reverses. This rule is important to remember when applying pressure loads or viewing the untransformed element forces or stresses. Untransformed directional element stress plots may appear strange when they are displayed by the postprocessor in SimXpert because the normals of the adjacent elements may be inconsistent. Remember that components of forces, moments, and element stresses are always output in the element coordinate system.

Figure 2

Thin Shell Element Geometry and Coordinate Systems

See Also: • LS-DYNA Keyword User’s Manual

Properties 279 Properties

Thick Shell Elements If the thickness dimension of your component is small, but not too small, in comparison to the other two, dimensions, you can model it with thick shell elements.

Figure 3

Typical Plate Element

*ELEMENT_TSHELL - Eight noded thick shell element useful for modeling thick plated components. Unlike the thin shell element, *ELEMENT_SHELL which represents the plate through the middle surface, and thickness, the 8-noded thick shell element represents plate as a hexahedron, the first four nodes representing the bottom surface, and the last four nodes representing the top surface. The thick

280 Properties

shell wedge element is defined by repeating the third for the fourth node, and repeating the seventh for the eighth node .

Figure 4

Thick Shell Element Connectivity

Properties 281 Properties

SECTION_TSHELL The properties of the thick shell elements are defined using the *SECTION_TSHELL entry. The format of the *SECTION_TSHELL entry is as follows:

Field

Contents

SECID

Section ID, to be referred by parts

ELFORM

Element formulation options = 1: 1point reduced integration (Default) = 2: Selective reduced 2X2 in plane integration = 3: Assumed strain 2X2 in plane integration

SHRF

Shear correction factor (a value of 5/6 recommended for solid section plate)

NIP

Number of through thickness integration points. (If NIP = 0, the Default value of 2 is used)

PROPT

Printout options = 0: Average resultants and fiber lengths = 1: resultants at plan points and fiber lengths = 3: Resultants, stresses at all points, fiber lengths

282 Properties

Field QR

Contents Quadrature rule LT 0.: Absolute value is used as the Quadrature rule EQ. 0.: Gauss Rule (up to five points permitted) EQ. 1.: Trapezoidal Rule

ICOMP

Flag for orthotropic/anisotropic layered composite material model = 0: Homogeneous =1: Composite

IRID

Integration Rule Id (User defined)

B1

Material angle (β1) at first integration point. This angle is measured with respect to the element edge n1-n2.

The orientation of the element coordinate system is determined by the order of the connectivity for the nodes. The element z-axis (the thickness direction) often referred to as the positive normal to the face connected by nodes n1, n2, n3, and is determined using the right-hand rule (cross product of edge vectors n1-n2 and n1-n3). Therefore, if you change the order of the nodal connectivity, the direction of this positive normal also reverses. This rule is important to remember when applying pressure loads or viewing the untransformed element forces or stresses. Untransformed directional element stress plots may appear strange when they are displayed by the postprocessor in SimXpert because the normals of the adjacent elements may be inconsistent. Remember that components of forces, moments, and element stresses are always output in the element coordinate system. See Also: • LS-DYNA Keyword User’s Manual Three-Dimensional Elements Whenever you need to model a structure that does not behave as a bar or plate structure under the applied loads, you need to use one or more of the three-dimensional elements. The three-dimensional elements are commonly referred to as solid elements. Typical engineering applications of solid elements include engine blocks, brackets, and gears. The Solid Elements in the Crash Workspace Include the Following: 1. 8 noded hexahedron 2. 6 noded pentahedron (degenerated from the 8-node hexahedron, by repeating node 4 for the last four nodes (n1, n2, n3, n4, n4, n4, n4, n4, n4) 3. 4 noded tetrahedron (degenerated from the 8-node hexahedron, by repeating node 5 for the sixth node, and repeating node 7 for the eighth node (n1, n2, n3, n4, n5, n5, n6, n4, n6)

Properties 283 Properties

4. 10 noded tetrahedron

Figure 5

Solid Elements

284 Properties

SECTION_SOLID The properties of the solid elements are entered on the *SECTION_SOLID form shown below:

Field

Contents

Title

Unique name identifying the section.

SECID

Section ID, to be referred by parts

Properties 285 Properties

Field ELFORM

Contents Element formulation options = 0: 1 point co-rotational for *MAT_MODIFIED_HONEYCOMB = 1: Constant stress solid element (Default) = 2: Fully integrated S/R solid = 3: Fully integrated quadratic 8 node element with nodal rotations = 4: S/R quadratic tetrahedron with nodal rotations = 5: 1 point ALE = 6: 1 point Eulerian = 7: 1 point Eulerian ambient = 8: acoustic = 9: 1 point co-rotational for *MAT_MODIFIED_HONEYCOMB = 10: 1 point tetrahedron = 11: 1 point ALE multi-material element = 12: 1 point integration with single material and void = 13: 1 point nodal sure tetrahedron for bulk forming = 14: 8 point acoustic = 15: 2 point pentahedron element = 16: 5 point 10 noded tetrahedron = 18: 8 point enhanced strain solid element for linear statics only

AET

Ambient element type (foe ELFORM = 7, 11 or 12) = 3: pressure outflow = 4: pressure inflow (Default for ELFORM = 7)

AFAC

Smoothing weight factor - simple average (if value is -1, smoothing turned off)

BFAC

Smoothing weight factor - volume weighting

CFAC

Smoothing weight factor - isoparametric

286 Properties

Field

Contents

DFAC

Smoothing weight factor - equipotential

START

End time for smoothing

END

Start time for smoothing

AAFAC

ALE advection factor

DX, DY, DZ

Normalized dilatation parameters of the kernel function in X, Y, and Z directions respectively

ISPLINE

Replaces choice for the EFG kernel functions definition in *CONTROL_EFG.. .EQ. 0: Cubic spline function (default) .EQ. 1: Quadratic spline function .EQ. 2: Cubic spline function with cubic shape

IDILA

Replaces choice for the normalized dilation parameter definition in *CONTROL_EFG.. .EQ. 0: Maximum distance based on the background elements .EQ. 1: Maximum distance based on the sourounding nodes

IEBT

Essential boundary condition treatment: .EQ. 1: Full transformation method .EQ. -1: w/o transformation .EQ. 2: Mixed transformation method .EQ. 3: Coupled FEM/EFG method .EQ. 4: Fast transformation method .EQ. -4: w/o transformation .EQ. 5: Fluid particle method for E.O.S and *MAT_ELASTIC_FLUID materials

Properties 287 Properties

Field IDIM

Contents Domain integration method: .EQ. 1: Local boundary integration (default) .EQ. 2: Two-point gauss integration .EQ. 3: Improved gauss integration for IEBT = 4 or -4

TOLDEF

Deformation tolerance for the activation of adaptive EFG Semi-Lagrangian and Eulerian kernel. = 0.0: Lagrangian kernel > 0.0: Semi-Lagrangian <0.0: Eulerian kernel.

See Also: • LS-DYNA Keyword User’s Manual One-Dimensional Elements A one-dimensional element is one in which the properties of the element are defined along a line or curve. Typical applications for the one-dimensional element include trusses, beams, and stiffeners. One-

288 Properties

dimensional elements discussed in this chapter include 3D beams, trusses, 2D axisymmetric shells, and 2D plane strain beam elements.

Figure 6

Beam Elements

SECTION_BEAM

Properties 289 Properties

The properties of the one dimensional elements are entered on the *SECTION_BEAM form shown below:

Field

Contents

SECID

Section ID, to be referred by parts

ELFORM

Element formulation options = 1: Hughes-Liu with cross section integration (Default) = 2: Belytscho-Schwer resultant beam = 3: Truss resultant = 4: Belytscho-Schwer full cross-section integration = 5: Belytscho-Schwer tubular beam full cross-section integration = 6: Discrete beam/cable = 7: 2D plane strain shell element (xy plane)

SHRF

Shear factor (5/6 recommended for rectangular section beam)

290 Properties

Field QR

Contents Quadrature rule or rule number for user defined integration rule = 1: 1 point integration = 2: 2X2 Gauss quadrature (default beam) = 3: 3X3 Gauss quadrature = 4: 3X3 Lobatto quadrature = 5: 4X4 Gauss quadrature = -n: where the absolute value of n is the number of the user defined rule.

CST

Cross section type (Not needed for truss, resultant beam, discrete beam, and cable elements) = 0: rectangular = 1 Tubular (circular only) = 2 Arbitrary (User defined integration rule)

SCOOR

Location for triad for tracking the rotation of the discrete beam element

NSM

Nonstructural mass per unit length

TS1

Beam thickness (for CST = 0.0, 2.0), or Outer diameter (CST=1.0) in s direction at node 1

TS2

Beam thickness (for CST = 0.0, 2.0), or Outer diameter (CST=1.0) in s direction at node 2

TT1

Beam thickness (for CST = 0.0, 2.0), or Outer diameter (CST=1.0) in t direction at node 1

TT2

Beam thickness (for CST = 0.0, 2.0), or Outer diameter (CST=1.0) in t direction at node 2

NSLOC

Location of reference surface normal to s axis (for Hughes-Liu beam elements only)

NTLOC

Location of reference surface normal to t axis (for Hughes-Liu beam elements only)

IRID

Integration Rule Id (User defined)

See Also: • LS-DYNA Keyword User’s Manual

Properties 291 Properties

Discrete Elements Discrete elements in SimXpert Crash comprise of spring and damper elements used between two nodes, or a node and ground. SECTION_DISCRETE The properties of the discrete elements are entered on the *SECTION_DISCRETE form shown below:

Field

Contents

SECID

Section ID, to be referred by parts

DRO

Displacement/Rotation Option: =0 for translational spring or damper =1 for torsional spring or damper

KD

Dynamic magnification vector

V0

Test velocity

CL

Clearance

FD

Failure deflection (twist, for DRO = 1. Negative for compression, positive for tension

CDL

Deflection (twist, for DRO = 1) limit in compression

TDL

Deflection (twist, for DRO = 1) limit in tension

See Also: • LS-DYNA Keyword User’s Manual Seatbelt Elements Seat belt elements are elements with single degree of freedom, connecting two nodes.

292 Properties

SECTION_SEATBELT The properties of the seat belt elements are entered on the *SECTION_SEATBELT form shown below:

Field SECID

Contents Section ID, to be referred by parts

See Also: • LS-DYNA Keyword User’s Manual Mass Elements Mass elements are used to defined lumped masses to nodes. In SimXpert crash workspace, the mass associated with the mass elements are assigned directly to the mass element, and hence no properties are needed to be created. See Also: • LS-DYNA Keyword User’s Manual

Element Integration SimXpert crash Workspace normally uses the recommended integration through thickness of beams and shell elements. However, you can use other through-thickness integration rules using • *INTEGRATION_BEAM for defining through thickness integration rules for the beam elements • *INTEGRATION_SHELL for defining through thickness integration rules for both the thin and

thick shell elements. See Also: • LS-DYNA Keyword User’s Manual

Properties 293 Properties

Hourglassing The advantage of the reduced integration elements is that the strains and stresses are calculated at the location that provide optimal accuracy, the so-called Barlow points. The reduced integration elements also tend to underestimate the stiffness of the element which often gives better results in a typically overly-stiff finite element analysis displacement method. An additional advantage is that the reduced number of integration points decreases CPU time and storage requirements. The disadvantage is that the reduced integration procedure may admit deformation modes that cause no straining at the integration points. These zero-energy modes cause a phenomenon called “hourglassing,” where the zero energy mode starts propagating through the mesh, leading to inaccurate solutions. This problem is particularly severe in first-order quadrilaterals and hexahedrals. To prevent these excessive deformations, an additional artificial stiffness is added to these elements. In this so-called hourglass control procedure, a small artificial stiffness is associated with the zero-energy modes. This procedure is used in many of the solid and shell elements in SimXpert crash Workspace Use the *HOURGLASS keyword data to define hourglass and bulk viscosity properties which are referenced via the HGID in the *part command. .

Figure 7

Hourglassing

See Also: • LS-DYNA Keyword User’s Manual

294 Properties

Meshing and Element Creation 293

Meshing and Element Creation

294 Meshing and Element Creation

Meshing and Element Creation Modeling Guidelines Finite element modeling in many ways is more like an art than a science since the quality of the results is dependent upon the quality of your model. One of the more common errors that a beginning finite element analyst makes in modeling is to simply simulate the geometry rather than to simulate both the geometry and the physical behavior of the real structure. The following modeling guidelines are provided to put a little more science back into the art of finite element modeling: • Choosing the right element. • Mesh transitions.

The above guidelines are by no means complete; however, they do serve as a good starting point. There is no better substitute for good modeling than experience. It is also good modeling practice to simulate and validate a new capability or a feature that you have not used before with a small prototype model before applying this feature to your production model. Model verification techniques are covered in Quality Checks, 297. SimXpert contains a large library of structural elements. In many situations several elements are capable of modeling the same structural effects. The criteria for the selection of an element may include its capabilities (for example, whether it supports anisotropic material properties), the amount of time required to run an analysis (in general, the more DOF an element has, the longer it runs), and/or its accuracy. In many cases the choice of the best element for a particular application may not be obvious. For example, in the model of a space frame, you may choose to use truss elements if bending or torsional stiffness is unimportant or to use the beam elements with axial, bending and torsional stiffness. You may even choose to represent the members with built-up assemblies of plate or solid elements. The choice of which type and number of elements to use depends primarily on your assessment of the effects that are important to represent in your model and on the speed and accuracy you are willing to accept. In this context, it is critical that you have a fairly good idea of how the structure will behave prior to generating your finite element model. The best source of such insight is usually experience with similar structures or components. In other words, understanding the load path is crucial in the selection of the appropriate element. In addition, a few hand calculations can usually provide a rough estimate of stress intensities. Such calculations are always recommended. If you do not have a fairly good idea of how the structure will behave, you may be misled by incorrect results due to errors or incorrect assumptions in your input data preparation. The following guidelines are provided to help you in selecting the “right” element for your task.

Meshing and Element Creation 295 Meshing and Element Creation

Avoid highly skewed elements (see Figure 1). The angle

α should be as close to 90 degrees as possible.

α

Figure 1

Highly Skewed Element

Aspect ratio is defined as l ⁄ ω (length/width). Very high aspect ratio (see Figure 2) should also be avoided in areas where there is a high stress gradient.

l ω Figure 2

Element with High Aspect Ratio

Warping is a measure of the amount the element deviates from being planar (see Figure 3). Element warping should be minimized. Element Mid-Plane

Figure 3

Highly Warped Element

Mesh Transitions Mesh transition can be a complicated subject. It may simply be used to refine the mesh in a particular area, connect different element types (for example, a CBAR element to a solid element), or provide transitions required to model the geometry of the structure. Two guidelines for mesh transitions are as follows: 1. Never place a mesh transition in an area of interest or in an area where there is a large variation in stress. 2. Mesh transitions should be located away from the areas of interest in a region.

296 Meshing and Element Creation

Due to incompatibilities between finite element types, any transition between different element types (even a transition from quadrilateral to a triangular elements) can result in local stress anomalies. Normally, these stress anomalies are localized and dissipate quickly as you move away from the transition. However, a problem arises when the transition occurs in an area of interest. In this case, the local stress rises (or decreases) due to the effect of the transition; in other words, the results may be conservative (or non-conservative) in an area near a transition. However, if this localized stress variation occurs away from areas of interest, the increase (or decrease) in stress caused by the transition should cause no concern. • Transition from a Coarse Mesh to a Fine Mesh

The transition from a coarse mesh to a fine mesh, or vice versa, may not always be an easy task. One common method of performing a transition is to use an intermediate belt of triangular elements as shown in Figure 4. Q4

Q4 T3

Q4

Q4 T3

Q4

Q4 T3

Q4

Q4 T3

Figure 4

T3

Q4

T3

Q4

Mesh Transition

Mesh Control Before you create elements, you should first specify a default mesh size by selecting Element Options from the Elements menu. Mesh sizes can also be set interactively using Mesh Size from the Elements menu. In addition you can also define hard points on curves or surfaces to ensure that a node is placed at that location. You do this using Create Hard Points from the Geometry menu. Mesh should have high density in areas of large stress gradients.

Meshing Automeshing You can use the selections under Automeshing to create multiple elements on geometry. • Automesh - Used to create quadrilateral and triangular plate/shell elements on surfaces. • Solid Mesher - Used to create a tetrahedral mesh inside bounding surfaces • Interactive Mesh Size - Interactively modifies the number of elements along a selected curve

Meshing and Element Creation 297 Meshing and Element Creation

Manual Meshing You can use the selections under Manual Meshing to create mesh without having surfaces. • 2-3-4 Line Mesh - Creates a mapped mesh by selecting 2,3, or 4 bounding curves. User can

modify the number of elements to be created on each curve. Set or modify the mesh elements parameters using Params button from the pick menu. • 3-4 Point Mesh - Creates mesh between the 3 or 4 selected points. You can specify the number of

elements to be created between each pair of selected points. Points should be selected in a circular manner. • Drag Mesh - Creates a solid or shell mesh by dragging elements or nodes along a specified

vector or curve. • Flange Creation - Creates a flange by dragging selected nodes through a specified width and

angle. • Linear Solid Mesh - Creates solid elements between two groups of shell elements. • Refine Mesh - Refines the selected mesh region to specified edge length, while maintaining

element connectivity with congruent elements. • Spin Mesh - Creates solid or shell elements by rotating shell elements or nodes through a

specified angle about a vector.

Merge Coincident Nodes Nodes along common edges of adjoining geometry entities need to match. If these nodes are not coincident, your model will have free edges or faces at these points. Always merge coincident nodes before analyzing your model using Merge Coincident Nodes from the Node menu.

Quality Checks Free Edges You can check that your model has completed merging coincident nodes by displaying free edges in your model. In Figure 5 the model is shown with free edges displayed by selecting Highlight FE Boundary from the View menu.The picture on the left shows the model with a solid horizontal line running through the middle. This indicates that a free edge exists there and the top and bottom are not connected. The

298 Meshing and Element Creation

picture on the right shows the model after the coincident nodes have been merged. The model is now one continuos piece. I

Free (unconnected) edge

Before

Figure 5

After

Free Edge Check - Before and After Merge Coincident Nodes

Consistent Plate Normals You can check the orientation of your plate elements using the Normals selection from the Element menu. When the pick box appears, in the Mode list, click Show Normal then click All. In Figure 6 you can see that these elements do not have consistent normals.

Figure 6

Inconsistent Normals

Meshing and Element Creation 299 Meshing and Element Creation

You can enforce consistent normals by now clicking Fix Normal in the Mode list and then selecting a reference element with the desired normal direction. You could also click Rev. Normal and then select the elements on which to reverse normals.

Figure 7

Consistent Normals

To turn off the display of normal vectors click Hide Normal in the Mode list then click All. Element Shape Checks The types of quality checks that SimXpert can perform on shell elements can be seen on the following form. It is accessed by selecting Quality/Quality from the Elements menu.

• Warp check: Evaluates how far out of plane the element ‘bends’. Warp is computed by

determining the angle between the normals of 2 triangular regions superimposed on the element. This check is also applicable to quad faces of solid elements. • Taper check: Compares the ratios of the lengths of opposite edges of an element. • Skew check: Compares the maximum angles between the element diagonals.

300 Meshing and Element Creation

• Interior Angle check: Evaluates the interior angles measured at each of the four (or 3) corner

nodes. If any element exceeds minimum or maximum tolerance levels specified for an element check, it is considered to have failed that test. SimXpert can compute a Quality Index which is a weighted composite of all the selected quality checks. You can toggle the display of the Quality Index from the Bottom Block by selecting Fringes On/Off from the FE-Grafix menu.

Elements that violate any of the activated quality criteria will be displayed in magenta.

Those elements color-coded red to orange have marginal quality. You can further investigate which specific tests your elements may be failing by selecting the individual quality measure from the FE-Qual

Meshing and Element Creation 301 Meshing and Element Creation

menu and your display will update accordingly. The following image shows the model now color-coded based on Warpage.

Once again, failed elements are shown in magenta. Elements with a high value that does not exceed the threshold are color-coded red or orange. Tools to Help Fix Poorly Shaped Elements • Manual - Element / Quality / Manual Fix - allows you to select a node and drag it to a new location. Element color coding will change in real time to feed back how the element’s quality is changing. Click the middle mouse button to finalize the new nodal location.

302 Meshing and Element Creation

• Mesh Quality - Element / Quality / Quick Quality - allows you to select elements for mesh

quality enhancement then select desired parameters as shown below:

• Fast Shell Enhancing attempts to fix failed elements only. Once they pass all selected criteria,

no further enhancement is attempted. • Slow Shell Enhancing attempts to fix failed elements and also to further improve all selected

elements. • All passes except Warp Enhancing will maintain nodes on the FE-Surface.

Warp Enhancing will move the node (within the specified tolerance) normal to the surface to decrease the warping.

Loads and Boundary Conditions 303

Loads and Boundary Conditions

304 Loads and Boundary Conditions

Loads and Boundary Conditions This chapter describes the loads and boundary conditions available when performing analysis with the SimXpert crash workspace. Each of the load types discussed may be applied to your model individually, or in any combination.

Supported Load and Constraint Types Most often, boundary conditions are imposed in the form of constraints on selected degrees of freedom on the model. Typically, several degrees of freedom are constrained to ground, using Single Point Constraints (SPC) boundary conditions. Besides single-point constraints, crash workspace provides a method of creating linear constraint relationships between several degrees of freedom. A third type of boundary conditions is the contact boundary condition for specifying that certain regions of the structure might be touching or separating during the simulation process. Contact boundary condition is an important feature of the crash workspace. This section discusses the single-point and multiple-point constraints. The rigid elements are discussed under Meshing, and the Contact is discussed under the section on contact. Single-Point Constraints A Single-Point Constraint (SPC) is a constraint that is applied to a single degree of freedom, which may be either a component of motion at a node or the displacement of a scalar point. The primary applications for single-point constraints are: 1. To tie a structure to ground. 2. To apply symmetric or anti symmetric boundary conditions by restraining the degrees of freedom that must have a zero value to satisfy symmetry or anti symmetry. Symmetry is discussed in the Modeling Guide. 3. To remove degrees of freedom that are not used in the structural analysis (that is, are not connected to any structural elements or otherwise joined to the structure). SPC BC • *BOUNDARY_SPC constraints usually specified at model boundaries to define rigid support points. These can also be used to apply an enforced nonzero displacement. Directions are in the applicable nodal coordinate system.

Loads and Boundary Conditions 305 Loads and Boundary Conditions

• *CONSTRAINED_LINEAR_OPTION defines linear constraint equation between

displacements and rotations defined in global (OPTION =GLOBAL), or local (OPTION =LOCAL) coordinate system. The constraint equation is generally of the form: n

C u k

k

= C0

k =1

where uk are the displacements/rotations, and Ck are the user defined coefficients. Nodal BC • FORCE and MOMENT -- Concentrated forces and moments, which are applied directly to nodes. The magnitude is entered directly. The direction is defined by selecting an appropriate degree-of-freedom (DOF) code. The node or nodes to which forces or moments are to be applied, can be selected directly or via node set. Follower forces and moments can also be applied. The temporal variation of the force or moment can be defined by using a load versus time curve (LCID). • Boundary Sliding Plane -- Boundary conditions at nodes on symmetry planes defined by

creating the symmetry plane. • Boundary Temperature -- Temperature Boundary Conditions at nodes for thermal loading, or

temperature dependent materials. • Initial Temperature -- Defines initial nodal temperatures. These can be applied either directly to

the nodes, or via node set. • Initial Foam Reference Geometry -- Defines reference configuration for the geometry of the

foam material for initialization of stresses in the foam. • Boundary Prescribed Motion -- Defines imposed (nonzero) nodal motion (velocity, acceleration,

or displacement) on nodes, node sets, or rigid bodies. Element BC • Load Shell -- Distributed pressure load applied to shell or thick shell elements, or element set. • Load Beam -- Distributed traction load along any local axis of beam elements or a set of beams. • Initial Strain Shell -- Applies initial strains to shell elements. • Initial Stress Shell -- Applies initial stresses to shell elements. • Initial Stress Beam-- Applies initial stresses to beam elements. • Initial Stress Solid -- Applies initial stresses to solid elements. • Initial Volume Fraction -- Defines initial volume fraction for different materials in multi-material

ALE, or in single material and void models. • Initial Momentum -- Defines initial momentum for depositing in solid elements, to simulate

impulse loading.

306 Loads and Boundary Conditions

Load Segment • Applies distributed pressure load over a triangular or quadrilateral segment defined by four nodes, over each segment in a segment set. Global BC • BOUNDARY_CYCLIC -- Defines nodes in boundary planes for cyclic symmetry • BOUNDARY_PRESCRIBED_MOTION -- Defines imposed (nonzero) nodal motion (velocity,

acceleration, or displacement) on nodes, node sets, or rigid bodies. • CONSTRAINED_ADAPTIVITY -- Defines adaptive constraints to constrain nodes to the

midpoint along edges of shell elements. • CONSTRAINED_GENERALIZED_WELD_BUTT -- Defines butt welds. Weld failures include

both plastic and brittle failures. Coincident nodes are permitted, provided local coordinates are defined. • CONSTRAINED_EULER_IN_EULER -- Defines coupling between materials in two

overlapping, and geometrically identical multi-materials Eulerian mesh sets. It also allows frictional contact between two or more Eulerian materials. • CONSTRAINED_GLOBAL -- Defines a global boundary constraint plane • CONSTRAINED_INTERPOLATION -- Defines an interpolation constraint whereby the motion

of a single dependent node is interpolated from the motion of a set of independent nodes. • CONSTRAINED_POINTS -- Defines constraint between two points with the specified

coordinates connecting two shell elements at locations other than nodal points. • CONSTRAINED_RIGID_BODIES -- Defines rigid body stoppers, to conveniently control the

motion of rigid tooling in metal forming applications. • CONSTRAINED_RIGID_BODY_STOPPERS -- Defines the merger of two rigid bodies • CONSTRAINED_SHELL_TO_SOLID -- Defines a tie (constraint) between the edge of a shell

and solid elements. • CONSTRAINED_TIE_BREAK -- Defines a tie (constraint) between the edge of a shell and

solid elements enabling local release as a function of plastic strain at the shell elements surrounding the interface nodes. • CONSTRAINED_TIED_NODES_FAILURE -- Defines a tied (constrained) node set with

failure based on plastic strains. • CONSTRAINED_JOINT_STIFFNESS -- Defines translational and rotational joint stiffness.

Options include FLEXION-TORSION, GENERALIZED, and, TRANSLATIONAL. • INITIAL_DETONATION -- Defines points to initiate high explosive detonations in parts • INITIAL_GAS_MIXTURE -- Defines initial temperature and density of different gas species in

*MAT_GAS_MIXTURE for the simulation of gas mixtures. • INITIAL_VELOCITY -- Defines initial nodal velocities using node set IDs. • INITIAL_VEHICLE_KINEMATICS -- Defines initial kinematical information such as

orientation, yaw, pitch, and roll axes for a vehicle.

Loads and Boundary Conditions 307 Loads and Boundary Conditions

• INITIAL_VELOCITY_RIGID_BODY -- Defines the initial translational and rotational

velocities at the center of gravity for a rigid body. This input overrides all other velocity input for the rigid body and the nodes which define the rigid body. • INITIAL_VELOCITY_GENERATION -- Defines initial velocity for rotating and translating

bodies. • INITIAL_VOID -- Defines initial voided part set or part numbers. • INITIAL_VOLUME_FRAC_GEOMETRY-- Defines initial volume fraction of different

materials in multi-material ALE, or in single material and void models. • Load Blast-- Defines an airblast function for the application of pressure loads due to explosives

in conventional weapons. • Load Body-- Defines body force loads due to prescribed base acceleration or angular velocity

using global axes definition. This load applies to all nodes in the model unless a part subset is specified via the *LOAD_BODY_PARTS keyword. • Load Body Generalized-- Defines body force loads due to prescribed base acceleration, or a

prescribed angular velocity over a subset of the model. The subset is defined by using nodes. • Load Body Parts-- Defines body force loads for nodes belonging to selected parts. • Load Brode-- Defines brode function for application of pressure loads due to explosives. • Load Density Depth -- Defines density versus depth for gravity loading for analyzing submerged

and underground structures. • Load Mask-- Defines distributed pressure load over a three dimensional shell part. The pressure

is applied to a subset of elements that lie within a fixed global box and lie either outside or inside of a closed curve in space which is projected onto the surface. • Load Rigid Body-- Defines concentrated nodal force to a rigid body. The force is applied at the

center of mass, or a moment is applied around a global or local axis. • Load SSA-- Defines a simple way of loading the structure to account for the effects of primary

explosion and the subsequent bubble oscillations. • Load SuperPlastic Form -- Defines loads for superplastic forming analysis. • Load Thermal Constant-- Defines nodal temperatures that remains constant (during the duration

of the analysis) or thermally loading a structure for structural analysis. • Load Thermal Load Curve -- Defines uniform (throughout the model) nodal temperatures that

can vary (in time) according to a load curve. • Load Thermal Variable -- Defines nodal sets giving the temperature that varies during the

duration of the analysis. • Airbag - Defines an airbag or control volume, providing a way of defining the thermodynamic

behavior of the gas flow into the airbag, and a reference configuration for the fully inflated bag. The available thermodynamic relationships include: Simple Pressure Volume, Simple Airbag Model, Adiabatic Gas Model, Wang Nefske, Wang Nefske Jetting, Wang Nefske Multiple Jetting, Load Curve, Linear Fluid, Hybrid, Hybrid Jetting, and Hybrid Chemkin. • Airbag Interaction -- Defines two connected airbags which vent into each other.

308 Loads and Boundary Conditions

• Airbag Reference Geometry -- Defines airbag reference geometry

LBC Sets Loads and boundary conditions can be grouped into sets. The applied loads can be applied independently or in combination. To group your applied loads into load sets select Create LBC Set from the BC menu.

Supply a name for your LBC set, then select the desired loads and boundary conditions.

Contact 309

Contact

310 Contact

Contact Overview The simulation of many physical problems requires the ability to model the contact phenomena. This includes analysis of interference fits, rubber seals, tires, crash, and manufacturing processes among others. The analysis of contact behavior is complex because of the requirement to accurately track the motion of multiple geometric bodies, and the motion due to the interaction of these bodies after contact occurs or breaks. This includes representing the friction between surfaces and heat transfer between the bodies if required. The numerical objective is to detect the motion of the bodies, apply a constraint to avoid penetration, and apply appropriate boundary conditions to simulate the frictional behavior and heat transfer. This section gives an overview of the methods used in the SimXpert crash Workspace for handling contact. Contact problems can be classified as one of the following types of contact. • Deformable-Deformable contact between single (self-contact), or multiple two- and three-

dimensional deformable bodies. • Rigid - Deformable contact between a deformable body and a rigid body, for two- or three-

dimensional cases. • Tied contact in two and three dimensions. This is a general capability for tying (bonding) two

deformable bodies, or a deformable body and a rigid body, to each other. Contact problems involve a variety of different geometric and kinematic situations. Some contact problems involve small relative sliding between the contacting surfaces, while others involve large sliding. Some contact problems involve contact over large areas, while others involve contact between discrete points. The approach adopted by SimXpert crash Workspace to model contact can be used to handle most contact problems.

Contact Methodology This section gives an overview of the methods used in the SimXpert crash Workspace for handling contact. Constraint Method One side of the contact interface is called the slave side, and the other is designated as the master side. Nodes lying in those surfaces are respectively referred to as the slave nodes and the master nodes. Constraints are imposed on the global equations by a transformation of the displacement components of the slave nodes along the contact interface. To keep the efficiency of the explicit time integration scheme, the mass is lumped to the extent that only the global degrees of freedom of each master node are lumped. Impact and release conditions are imposed to ensure the conservation of momentum. If the mesh in the master surface zone is finer than the slave surface zone, master nodes can penetrate through the slave surface without resistance, and create incorrect solution, especially if the interface pressures are too high. Better choice of master and slave zoning would minimize such errors in some

Contact 311 Contact

cases. However, in some modeling situations (e.g. modeling of airbags in automotive crash applications) good zoning in the initial configuration may be poor zoning later as the deformation progresses. Penalty Method The penalty method places normal interface springs between all penetrating nodes and the contact surface. Momentum is conserved exactly without the necessity of imposing impact and release conditions. Currently there are three formulations of the penalty algorithm. Standard Penalty Formulation: In this formulation, the interface stiffness is chosen to be approximately of the same order of magnitude as the stiffness of the interface element normal to the interface. If interface pressures become large, unacceptable penetration may occur. The usual remedy of scaling up the penalty stiffness, and scaling down the time step size increase the cost of the simulation. Soft Constraint Penalty Formulation: In this formulation, in addition to the master and slave contact stiffness, an additional stiffness (called the stability contact stiffness) which is based on the stability (Courant’s criterion) of the local system comprised of two masses (segments) connected by a spring is added. The stability contact stiffness kcs is calculated as: kcs = 0.5. SOFSCL. m*. (1/(Δtc(t)) where, SOFSCL is the Soft Constraint Penalty Scale factor, m* is a function of the mass of the slave node and the master nodes, and Δtc is set to the initial solution time step. Segment-based Penalty Formulation: This formulation uses a slave segment-master segment approach instead of the slave node-master segment approach. It is especially very efficient for airbag self-contact during inflation and complex contact conditions. Accounting for Shell Thickness Shell thickness effects as well as change in thicknesses are accounted for in the crash Workspace. Contact Damping Viscous contact damping can be added to all contact options including single surface contact. It allows to damp out oscillations normal to the contact surfaces during metal forming operations, and it also works effectively in removing high frequency noise in problems involving impact. Friction Friction in crash Workspace is based on a Coulomb formulation See “LS-DYNA Theory Manual” for a complete description of the friction formulation.

312 Contact

Tied Contact Tied contact or tied interfaces provides a convenient way of modeling with dissimilar (non congruent) meshes across an interface. This can often decrease the amount of effort required to generate meshes since it eliminates the need to match nodes across common faces of parts.

Contact Types Different types of contact may be defined in SimXpert crash. Some of the most common contact types are listed here. Refer to the “LS-DYNA Keyword User’s Manual” for a more complete and detailed description. • Automatic Nodes to Surface • Automatic Single Surface • Automatic One way Surface to Surface • Automatic Surface to Surface • Nodes to Surface • Surface to Surface • Tied Nodes to Surface

Contact 313 Contact

• Tied Shell Edge to Surface • Tied Surface to Surface • Airbag Single Surface • Rigidwall Geometric Flat • Rigidwall Geometric Cylinder • Rigidwall Geometric Sphere

Contact Parameters A list of the most common contact parameters are described here. Refer to the “LS-DYNA Keyword User’s Manual” for a more complete and detailed description.

Variable

Description

FS

Static coefficient of friction

FD

Dynamic coefficient of friction

DC

Exponential decay coefficient

VC

Coefficient for viscous friction

VDC

Viscous damping coefficient in percent critical

PENCHK

Small penetration option in contact search.

BT

Birth time of contact (contact surface becomes active at this time)

DT

Death time of contact (contact surface is deactivated at this time)

SFS

Scale factor on default slave penalty stiffness.

SFM

Scale factor on default master penalty stiffness

SST

Optional thickness for slave surface (overrides true thickness)

MST

Optional thickness for master surface (overrides true thickness)

SFST

Scale factor for slave thickness (scales true thickness)

SFMT

Scale factor for master thickness (scales true thickness)

FSF

Coulomb friction scale factor

vs.F

Viscous friction scale factor

CF

Thermal conductivity of fluid between the slide surfaces

FRAD

Radiation factor between the slide surfaces

HTC

Heat Transfer conductance for close gaps

GCRIT

Critical gap. Use Heat Transfer conductance defined (HTC) for gap thickness less than the value of GCRIT

GMAX

No thermal contact if gap is greater than GMAX

314 Contact

Variable

Description

CD_FAC

A multiplier used on the element characteristic distance for the search algorithm.

SOFSCL

Scale factor for constraint forces of soft constraint option

LCIDAB

Load Curve Id defining thickness of airbag (used in airbag contacts)

MAXPAR

Maximum parametric coordinate in segment search.

EDGE

Edge to edge penetration check

DEPTH

Option to search depth in automatic contact

BSORT

Number of cycles between bucket sorts

FRCFRQ

Number of cycles between contact force updates for penalty contact formulations

PENMAX

Maximum penetration distance

THKOPT

Thickness option

SHLTHK

Shell thickness option

SNLOG

Option to enable/disable shooting node logic in thickness offset contact

ISYMB

Symmetric plane option (set to 1, to retain the correct boundary conditions in models with symmetry.)

I2D3D

Segment searching option

SLDTHK

Solid element thickness (a nonzero positive value activates the contact thickness offsets in the contact algorithm where offsets apply)

SLDSTF

Solid element stiffness (a nonzero positive value overrides the bulk modulus taken from the material model referenced by the solid element)

IGAP

Flag to improve implicit convergence behavior at the expense of creating some sticking, if parts attempt to separate

IGNORE

Option to allow/ignore initial penetrations

trackpen

Flag for initial penetration compensation

bucket

Bucket sorting frequency

lcbucket

Load Curve Id defining bucket sorting frequency vs. time

nseg2trac

Number of segments to track for each slave node

initiator

Number of iterations for initial penetration checking

Simulation 315

Simulation

316 Time Step Control

Time Step Control During the solution a new time step is estimated by taking the minimum value over all the elements in the model:

Δt n+1 = a ⋅ min{Δt1, Δt2 , Δt3,..., ΔtN } where, N is the number of elements, and a is the scale factor. For stability reasons the scale factor a is typically set to a value of 0.90 (default) or smaller. Time Step for Solid Elements A critical time step size, Δte, is computed for solid elements from:

Δte =

{ Q + (Q

Le 2

1/ 2 + c 2 )  

}

where, c is the adiabatic speed of sound, Q is a function of the bulk viscosity coefficients C0 and C1. For elastic materials with a constant bulk modulus c can be computed as:

c=

E (1 − υ ) (1 + υ )(1 − 2υ ) ρ

where, E, ν, and ρ are respectively the Young’s modulus, Poisson’s ratio, and density.

C1c + C0 Le εkk for εkk < 0 Q= for εkk ≥ 0 0 where, Le is a characteristic length calculated as the minimum altitude (for 4-node tetrahedrons), or the ratio of the element volume to the area of the largest face (for 8-node hexahedra) Time Step for Shell Elements For the shell elements, the time step size is given by:

Δte =

Ls c

Simulation 317 Time Step Control

where, Ls is the characteristic length, and c is the speed of sound:

E ρ (1 −ν 2 )

c=

Three user options exist for selecting the characteristic length Ls. In the first (default) option, Ls is given by: e

Ls =

(1 + β ) As max( L1 , L2 , L3 , (1 − β ) L4 )

where, β = 0 for quadrilateral, and 1 for triangular shell elements, As is the area, and Li (i = 1, 2, 3, 4) is the length of the sides defining the shell elements. In the second option, the following more conservative value is used for Ls:

Ls =

(1 + β ) As max( D1 , D2 )

where, Di (i = 1, 2) is the length of the diagonals. The third option, which provides the largest time step size, and is often used for triangular shell elements with very small altitudes uses the following expression for Ls:

  (1 + β ) As , min( L1 , L2 , L3 , L4 + β 1020 )  Ls = max   max( L1 , L2 , L3 ,(1 − β ) L4 )  Time Step for Beam and Truss Elements For the Hughes-Liu beam and truss elements, the time step size is given by:

Δt e =

L c

318 Time Step Control

where, L is the length of the element, an c is the speed of sound calculated as:

c=

E

ρ

The Belytscho beam also uses smaller of the values given by:

Δt e =

L c

and

Δt e =

.5L 3 1   + 2 c 3I  2 12 I + AL AL 

where, I and A are the maximum value of the moment of inertia, and the area of the beam cross section respectively. Time Step for Discrete Elements For spring elements there is no wave propagation speed c to calculate the critical time step size. However, based on the maximum eigenvalue of the spring with the nodal masses M1, M2 attached to the nodes connected to the spring, the critical time step size can be computed as:

Δte = 2

2M 1M 2 k ( M1 + M 2 )

Simulation 319 Output Control

Output Control The Control and the database options are used to set solution and output options for the analysis.

320 Control

Control The Control options are used to set solution options such as analysis duration (*CONTROL_TERMINATION), adaptive meshing (*CONTROL_ADAPTIVE), parallel processing (*CONTROL_PARALLEL), and output options such as energy (*CONTROL_ENERGY), output interval (*CONTROL_OUTPUT). Refer to the LS-DYNA Keyword user’s Manual for a complete list of the Control cards and options. These control options can be set, and or changed from the SimXpert crash Workspace. Many of these options have default settings which work pretty well in most situations. However, a set of standard or user selected control options can be imported from an existing LS-DYNA keyword file, for use either on an as-is basis, or to be selectively modified in the crash workspace GUI.

Database The LS-DYNA Database options define options for output files containing results information for post processing. For example, the use of the *DATABASE_BINARY_D3_PLOT card lets you select the time interval (DT) between output for the d3plot files. Refer to the “LS-DYNA Keyword User’s Manual” for a complete list of the database cards and options. These database options can be set, and or changed from the SimXpert crash Workspace. Many of these options have default settings which work pretty well in most situations. However, a set of standard or user selected control options can be imported from an existing LS-DYNA keyword file, for use either on an as-is basis, or to be selectively modified in the crash workspace GUI.

Simulation 321 Perform the Simulation

Perform the Simulation To perform the analysis, export an LS-DYNA keyword file (File -> Export -> Dyna Model). This will create a keyword input file which can then be used to perform the simulation with LS-DYNA on a computer where it is installed.

Manually Invoking LS-DYNA As a part of SimXpert Installation, the LS-DYNA Analysis Code solver is installed in a subdirectory under the main installation directory and can be invoked directly. Should you need to manually invoke LS-DYNA, run the executable found under the SimXpert installation directory. To invoke LS-DYNA from Linux32: /Nastran/md2009/dyna/linux32/run_dytran jid=jobid.key iam=simxcr From Linux64: /Nastran/md2009/dyna/linux64/run_dytran jid=jobid.key iam=simxcr From Windows32: /Nastran/md2009/dyna/win32/run_dytran jid=jobid.key iam=simxcr From Windows64: /Nastran/md2009/dyna/win64/run_dytran jid=jobid.key iam=simxcr where jobid.key is a LSDYNA input deck. For Linux32, the default INSTALLROOT Path for SimXpert R4 is /msc/SimXpert/R4 For Linux64, the default INSTALLROOT Path for SimXpert R4 is /msc/SimXpert_x64/R4 For Windows32/64, the default INSTALLROOT Path for SimXpert R4 is C:\MSC.Software\SimXpert\R4

322 Perform the Simulation

Example - Crushing of a Thin Square Tube 323

Example - Crushing of a Thin Square Tube

324 Crushing of a Thin Square Tube

Crushing of a Thin Square Tube Problem Description A square cross section thin tube is to be simulated for crushing by a rigid wall moving with an initial velocity toward one end of the tube, while the other end is fixed. The basic FEA model containing the nodes and the elements is imported from a Nastran input file. Complete the crush model with materials, sections, boundary conditions, loads, and analysis and output options for performing the crush simulation. Some Key Data: Cross-section of the tube:

69.954 mm X 69.954 mm

Length of the tube:

320 mm

Thickness of the tube:

1.2 mm

Weight of the rigid wall:

0.4 ton

Initial velocity of the rigid wall: 5646 mm/sec

Steps: Following are the steps to complete the crush model.

1. Launch SimXpert Select Structures as the Workspace 2. Select the Solver Card as the GUI Options Tools -> Options -> GUI Options Select Solver Card Click Apply 3. Set the Units for the model Click Units Manager Click Standard Units Select mm, t, s as the units for Length, Mass, and Time respectively Click OK Click OK

Example - Crushing of a Thin Square Tube 325 Crushing of a Thin Square Tube

4. Import the FEA mesh from a MSC.Nastran input file File -> Input -> Nastran ... Select the file, square_tube_nast.bdf Hint:

You can find the above file in the PartFiles folder under the help folder in the SimXpert installation directory. Click Open Close the (pop-up) Notepad window (nastran.err - Notepad) The imported FEA mesh represents a quarter model of the thin square tube.

Figure 1

Quarter model of a square section tube

5. Switch the workspace to crash: Set workspace to crash 6. Create the material: Materials and Properties-> MAT [1 to 20] -> [003]MAT_PLASTIC_KINEMATIC Enter steel as the Title for the material Enter value for RO: 7.85E-9

326 Crushing of a Thin Square Tube

Enter value for E: 1.994E5 Enter value for PR: 0.30 Enter value for SIGY: 3.366E2 Enter value for ETAN: 1 Enter value for BETA: 1 Click OK 7. Create properties for the shell elements: Materials and Properties-> Section -> SECTION_SHELL Select 2 for ELFORM Enter value for SHRF: 1. Enter value for NIP: 3 Note: Hit the Enter key, after typing 3 for NIP. Otherwise, the change will not be made. Enter value for T1: 1.2 Enter value for T2: 1.2 Enter value for T3: 1.2 Enter value for T4: 1.2 Click OK 8. Assign property and material to the part: Right click on the (part) PSHELL... in the Model Browser Click Properties on the pop-up window Double click on the SECID data box, and click Select Select SECTION_SHELL_1 from the Select a PSECTION form Click OK Double click on the cell below MID, and click Select Select steel from the Select a Material form Click OK Set the value for ADPOPT to 1 Click Modify Click Exit

9. Create the boundary conditions for the tube:

Example - Crushing of a Thin Square Tube 327 Crushing of a Thin Square Tube

LBCs -> LBC -> SPC -> Boundary SPC Make sure all six DOFs are checked-in (selected) Click Store Click Exit Pick all the nodes on the bottom of the tube Click Done on the Pick panel This fixes the bottom edge of the tube against all translations and rotations.

328 Crushing of a Thin Square Tube

Top edge

z-symmetry edge

x-symmetry edge

Bottom edge (fixed)

Figure 2

Boundary conditions for the tube model

Example - Crushing of a Thin Square Tube 329 Crushing of a Thin Square Tube

LBCs -> LBC -> SPC -> Boundary SPC Check in DOFX, DOFRY, DOFRZ Click Store Click Exit Pick all the nodes on the x-symmetry edge, except the node on the bottom edge. Click Done on the Pick panel This imposes the symmetric boundary condition on the x-symmetry edge. LBCs -> LBC -> SPC -> Boundary SPC Check in DOFZ, DOFRX, DOFRY Click Store Click Exit Pick all the nodes on the z-symmetry edge, except the node on the bottom edge. Click Done on the Pick panel This imposes the symmetric boundary condition on the z-symmetry edge. 10. Create a constrained node set on all the nodes on the top edge: Nodes/Elements ->Elements -> Create -> Rigid -> Constrained Node Set Set DOF to 2 Click Store Click Exit Pick all the nodes on the top edge Click Done on the Pick panel 11. Create mass elements to represent the rigid wall: Elements -> Create -> 1 Noded -> Element Mass Enter value for MASS: 0.01 Click Store Click Exit Pick all the nodes on the top edge, except two nodes where the symmetry edges meet the top edge. Click Done on the Pick panel

330 Crushing of a Thin Square Tube

Elements -> Create -> 1 Noded -> Element Mass Enter value for MASS: 0.005 Click Store Click Exit Pick the two nodes where the symmetry edges meet the top edge Click Done on the Pick panel 12. Create the initial velocity on the top nodes: LBCs -> LBC -> Nodal BC-> Initial Velocity Enter value for VY: -5646 Click on Define App Region Pick all the nodes on the top edge Click Create 13. Create an auto single surface contact: LBCs -> Contact-> Automatic -> Auto Single Surface Click OK on the Auto Single Surface form 14. Select the dyna control options: Parameters -> Control -> [A to C] -> CONTROL ADAPTIVE Enter value for ADPFREQ: 1.E-4 Enter value for ADPTOL: 5 Select value for ADPOPT: 2 Enter value for MAXLVL: 2 Enter value for ADPSIZE: 0 Click OK Control -> [N to Z] -> CONTROL TERMINATION Enter value for ENDTIME: 3.E-3 Click OK Control -> [D to H] -> CONTROL ENERGY Select value for HGEN: 2 Select value for RWEN: 2 Select value for SLNTEN: 2 Select value for RYLEN: 1

Example - Crushing of a Thin Square Tube 331 Crushing of a Thin Square Tube

Click OK Control -> [N to Z] -> CONTROL OUTPUT Select value for NPOPT: 1 Select value for NEECHO: 3 Click OK Control -> Title ->TITLE Enter value for Title: Crushing of a thin square tube Click OK 15. Select the dyna database options: Database -> OPC -> DATABASE BINARY option Enter valuEnter value for DT_D3PLOT: 1.E-4 Check in the IOPT select box, and set its value to 1 Click OK Database -> OPC -> DATABASE option Enter value for DT_GLSTAT: 2.E-5 Enter value for DT_MATSUM: 2.E-5 Click OK 16. Save the SimXpert database: File -> Save As Enter name for the file: square_tube_crush Click Save 17. Run the Simulation: Rght-click on Simulations Enter name for Fle name: square_tube_crush Click Save 18. Exit from SimXpert: File -> Exit

19. Post-process the Results in ls-prepost

332 Crushing of a Thin Square Tube

Figure 3

Von Mises Stress at Time = 0.003