Nodal Pressure.pdf

14/03/2019

Nodal Pressure

Nodal Pressure Using Nodal Pressure, you can apply pressure on element faces. You must create a node based named selection before you can apply a Nodal Pressure. It is applicable for solid and surface bodies only. Specifically, an elemental face pressure is created only if all of the nodes of a given element face (including midside) are included. If all nodes defining a face are shared by an adjacent face of another selected element, the face is not free and will not have a load applied. Warning: For application to surface bodies, the MAPDL solver logic for this load is such that if all of the nodes of a shell element are specified, then the load is applied to the whole element face. However, if only some nodes are specified on an element and those nodes constitute a complete external edge, then an edge pressure is created. Therefore, it is critical that you make sure that you have not selected nodes that constitute only a free shell edge. This is because shell edge pressures are input on a per-unit-length basis, and Mechanical treats this load always as a per-unit-area quantity. See the SHELL181 Element Description for more information. Nodal Pressures applied to shell bodies act in the opposite direction of geometrybased pressures. Note: A Nodal Pressure may be added during Solution Restart without losing the restart points.

Analysis Types Nodal Pressure is available for the following analysis types: Eigenvalue Buckling (for Nonlinear-based Eigenvalue Buckling Analysis only) Harmonic Response (Full) Analysis Using Pre-Stressed Structural System Static Structural Transient Structural

Common Characteristics The following section outlines the common boundary condition characteristics that include application requirements of the boundary condition, support limitations, as well as loading definitions and values. Dimensional Types

Supported. 2D Simulation: Supported. 3D Simulation:

Geometry Types: Geometry types supported for the Nodal Pressure boundary condition include: https://www.sharcnet.ca/Software/Ansys/16.2.3/en-us/help/wb_sim/ds_Nodal_Pressure.html

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Nodal Pressure

Supported. Surface/Shell: Supported. Solid:

Wire Body/Line Body/Beam: Not Supported. Topology: The Nodal Pressure boundary condition is scoped via node-based Named Selections only. See the Specifying Named Selections by Direct Node Selection Help section for more information. Note: The Nodal Pressure boundary condition supports spatially varying loading on the scoped nodes for Static and Transient analyses only. For Eigenvalue Buckling and Harmonic Response analyses, only constant loading conditions are supported.

Boundary Condition Application To apply a Nodal Pressure: 1. On the Environment toolbar, click Direct FE > Nodal Pressure. Or, right-click the Environment tree object or the Geometry window and select Insert>Nodal Pressure. 2. Click the Named Selection drop-down list, and then select the node-based Named Selection to prescribe the scope of the Nodal Pressure. 3. Enter a magnitude for the load.

Details View Properties The Details View selections are described below. Category

Scope

Fields/Options/Description Scoping Method: read-only field that displays scoping method Named Selection. Named Selection: drop-down list of available node-based Named Selections.

https://www.sharcnet.ca/Software/Ansys/16.2.3/en-us/help/wb_sim/ds_Nodal_Pressure.html

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Nodal Pressure

Category

Fields/Options/Description Type: read-only field that displays boundary condition type Pressure. Define By: read-only field that displays that the boundary condition is acting Normal To the surface to which it is attached.

Definition

Magnitude: input field to define the magnitude of the boundary condition. This value can be defined as a Constant, in Tabular form, or as a Function. Note: Spatially varying loading (Tabular/Function) is supported for Static and Transient analyses only. For Eigenvalue Buckling and Harmonic Response analyses, only constant loading conditions are supported. Suppressed: includes or excludes the boundary condition in the analysis.

Note: To apply a node-based pressure, the named selections that you create must include nodes such that they define an element face. Two Nodal Pressure objects that have same scoping do not produce a cumulative loading effect. The Nodal Pressure object that was specified last takes priority and is applied, and as a result, the other Nodal Pressure object is ignored. A load applied to a geometric entity and a Nodal Pressure produce a resultant effect. You can apply a spatially varying Nodal Pressure to scoped nodes.

MAPDL References and Notes For more information on the solver representation of this load, reference the SF command in the .

Mechanical APDL Command Reference

Release 16.2 - © SAS IP, Inc. All rights reserved.

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