WORKSHOP 5
Spatial Variation of Physical Properties Aluminum Steel
45°
Radius 1” Radius 3” Radius 4”
Objective: ■ Model the variation of physical properties as a function of spatial coordinates.
MSC.Nastran 120 Exercise Workbook
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MSC.Nastran 120 Exercise Workbook
Spatial Variation of Physical Properties
WORKSHOP 5
Model Description: Create a model of a tapering annular plate. Due to the model’s symmetry only a 45° slice of the plate will be modeled. Define spatially varying material and physical properties for the plate. Figure 5.1
Surface 2 Aluminum
Surface 1 Steel
y
Thickness, inches
z
45°
x 1.0”
2.0”
1.0”
0.20 0.10 4
1 3 Radial Distance, r, inches
Table 5.1 - Finite Element Properties Analysis Code:
MSC.Nastran
Element type:
Quad4
Element Global Edge Length:
0.5
Table 5.2 - Material Properties Material:
Steel
Aluminum
Modulus of Elasticity:
30E+06
10E+06
Poisson Ratio:
0.30
0.20
Density:
7.324E-04
2.588E-04
MSC.Nastran 120 Exercise Workbook
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Suggested Exercise Steps: ■ Create a new database called circular_plate.db. ■ Create geometry that represents a 45° slice of the circular plate shown in Figure 5.1. ■ Create a finite element mesh using the information listed in Table 5.1. ■ Define a cylindrical coordinate frame whose origin is located at [0,0,0], where the R-, T-, Z-axis are aligned with the X-, Y-, Z-axes respectively of the global coordinate system. ■ Using the cylindrical coordinate frame, define a spatially varying field named thickness_spatial, that represents the model’s thickness. Verify the field by displaying an XY-plot. ■ Define material properties using the material constants shown in Table 5.2. ■ Inspect the constitutive (stiffness) matrices, Cijkl, of each material type. ■ Define element properties assigning the material type and element thickness to the correct region of the model. ■ Verify that the spatial variation of the element thickness has been assigned correctly to the model by rendering a scalar plot of the thickness.
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WORKSHOP 5
Spatial Variation of Physical Properties
Exercise Procedure: 1.
Create a New Database and name it circular_plate.db. File/New... New Database Name
circular_plate
OK 2.
Change the Tolerance to Default and the Analysis Code to MSC.Nastran in the New Model Preferences form. Verify that the Analysis Type is Structural. New Model Preference Tolerance
Default
Analysis Code:
MSC/NASTRAN
Analysis Type
Structural
OK NOTE: Whenever possible, toggle off the ❑ Auto Execute option by left clicking the check box. 3.
Create geometry that represents a 45° slice of the circular plate shown in Figure 5.1. Create the 45 degree slice of the circular plate by creating two adjacent surfaces that lie in the global xy-plane. The two surfaces meet along the material boundary. See Figure 5.1 for the dimensions. The model should look similar to Figure 5.2.
MSC.Nastran 120 Exercise Workbook
5-5
Figure 5.2
4.
Create a finite element mesh. Finite Elements Action:
Create
Object:
Mesh
Type:
Surface
Global Edge Length
0.5
Element Topology
Quad 4
Surface List
Surface 1, 2
Apply The mesh should resemble Figure 5.3.
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MSC.Nastran 120 Exercise Workbook
Spatial Variation of Physical Properties
WORKSHOP 5
Figure 5.3
5.
Create a cylindrical coordinate frame located at [0,0,0] with the R-, T-, Z-axis are aligned with the X-, Y-, Z-axes, respectively, of the global coordinate system. Geometry Action:
Create
Object:
Coord
Method:
3Point
Type:
Cylindrical
Origin
[0, 0, 0]
Point on Axis 3
[0, 0, 1]
Point on the Plane 1-3
[1, 0, 0]
Apply 6.
Use the cylindrical coordinate frame to define a spatially varying field named thickness_spatial, which represents the model’s thickness. Verify the field values using an XY-plot. Fields Action:
Create
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Object:
Spatial
Method:
Tabular Input
Field Name
thickness_spatial
Coordinate System
Coord 1
Active Independent Variable
R
Input Data... To describe the thickness across the plate, enter three thickness values into the table as shown in Figure 5.4. Figure 5.4
OK Apply 6a.
Verify the field using a XY plot. Fields Action: Select Field to Show
Show thickness_spatial
Specify Range... Use Existing Points OK Apply The plot should appear in a new window resembling Figure 5.5. 5-8
MSC.Nastran 120 Exercise Workbook
WORKSHOP 5
Spatial Variation of Physical Properties
Figure 5.5
MSC.Nastran 120 Exercise Workbook
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7.
Close the XY Plot. XY Plot Action:
Delete
Object:
XY Window
Existing XY Windows
XY Result Window
Apply Chose Yes when asked about deleting the XY result window. 8.
Define material properties. Materials Action:
Create
Object:
Isotropic
Method:
Manual Input
Material Name
steel
Input Properties... Elastic Modulus
30.0E6
Poisson Ratio
0.3
Density
0.0007324
OK Apply Define a second material for the model. Materials Action:
Create
Object:
Isotropic
Method:
Manual Input
Material Name Input Properties...
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MSC.Nastran 120 Exercise Workbook
alum
Spatial Variation of Physical Properties
WORKSHOP 5
Elastic Modulus
10.0E6
Poisson Ratio
0.2
Density
0.0002588
OK Apply 9.
Inspect the constitutive (stiffness) matrices, Cijkl, of each material. To verify the material constants, select Show from the Action option menu on the Materials form. Action:
Show
Material Name
steel
Show Material Stiffness... 10.
Define element properties for the model using fields. Properties Action:
Create
Dimension:
2D
Type:
Shell
Property Set Name
prop_1
Input Properties... Material Name
m:steel
Thickness
f:thickness_spatial
OK Select Application Region
Surface 1
Add Apply 10a. Repeat step 10 to define element properties for Surface 2.
MSC.Nastran 120 Exercise Workbook
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11.
Verify element properties using a scalar plot of the thickness. Properties Action:
Show
Existing Properties
Thickness
Display Method
Scalar Plot
Group Filter
Default_group
Apply It may be necessary to reset the range to span the actual property range. Display/Ranges... Fit Results Calculate Apply Cancel The Viewport will appear as follows. Figure 5.6
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WORKSHOP 5
Spatial Variation of Physical Properties
To clear out the scalar plot, clean up the display using the Reset Graphics tool on the Patran menu bar. Reset Graphics
Quit MSC.Patran after finishing this exercise.
MSC.Nastran 120 Exercise Workbook
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MSC.Nastran 120 Exercise Workbook