Specifying Nastran GEOMCHECK options

When you solve a model in Nastran, Nastran performs two categories of geometry checks on the elements in your model:

• System level checks which determine if the elements’ geometry is adequate for finite element matrix generation. There is no user control for these checks.

• User controlled element checks. In Nastran, you use the GEOMCHECK executive control statement to control the checks performed and the threshold values for those checks.

In Pre/Post, you use a Geometry Check Options modeling object to control the values that Nastran uses to evaluate the quality of the elements in your model prior to a solve. The options in the Geometry Check Options dialog box let you override Nastran's default element quality threshold values with your own values. This lets you permit an element that fails with the default values to pass the quality checks with reasonably modified values. For more information, see Geometry Check Options dialog box (Nastran/Multiphysics).

Note:

You should always use good engineering judgment when you modify these default values.

When you solve or export your model, the options in the Geometry Check Options dialog box define a GEOMCHECK executive control statement in your Nastran input file.

For more information, see the following topics in the Simcenter Nastran User's Guide:

• Element Geometry Checks

• Using the GEOMCHECK Statement

• Geometry Test Descriptions

Geometry Check Options control criteria for optional tests

The options that you specify in the Geometry Check Options dialog box control the number and severity of certain informational and warning messages produced by optional geometry checks performed by Nastran. These checks are different from a series of mandatory system-level checks that Nastran performs.

Nastran performs the system-level checks of the element quality regardless of whether you define any Geometry Check Options. There is no user control for the system controlled checks. The system controlled checks always produce a fatal error if Nastran finds an element prevents the formulation of the finite element matrix.

Geometry Check Options are separate from element shape checks

The element quality checks performed by the Model Check command let you evaluate the quality of the elements in your model before you perform an analysis. The options that you specify in the Geometry Check Options dialog box control the number and severity of certain informational and warning messages produced by optional geometry checks performed by Nastran during the solve itself. The options in theGeometry Check Options dialog box are separate from the threeshold values that the Model Check command uses to evaluate element quality. Changes you make to the Geometry Check Options do not impact the Model Check threshold values, and vice versa.

Where do I find it?

Application	Pre/Post
Prerequisite	An active Simulation file with Simcenter Nastran, MSC Nastran, or Simcenter 3D Multiphysics as the specified solver
Command Finder	Modeling Objects →Type list→Geometry Check Options
Menu	Insert→Modeling Objects→Type list→Geometry Check Options

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Specifying Nastran GEOMCHECK options, Simcenter 3D 2021.1 Series

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