Associative and non-associative FEM files

Associative FEM files

An associative FEM file has the following characteristics:

• It contains a pointer to a CAD part (.prt) file.

• It reads Parasolid geometry from the part file and converts it to polygon geometry that is suitable for meshing.

• It checks the status of the part file and updates the polygon geometry as needed. Both the FEM file and the CAD part must be loaded.

Left: Parasolid geometry in the CAD part. Right: Derived polygon geometry in an associative FEM file. Sliver faces and small edges are abstracted away.

The polygon geometry in the FEM file supports both automatic and manual modifications of surface topology to improve mesh quality. Polygon geometry abstraction removes design artifacts such as sliver faces, small edges, and isthmus conditions. This allows you to mesh the geometry at a level of detail that sufficiently captures the design intent relevant to a particular finite element analysis.

Because multiple FEM files can reference the same part, you can build different FEMs for different types of analyses.

The associated CAD part file may be:

• A CAD assembly.

• A CAD component or piece part.

• An idealized part in Pre/Post. An idealized part is a special assembly file that promotes concurrent engineering and team-based workflows.

Multiple FEM files can be associated to the same CAD part file.

A FEM file associated to a CAD part file

A FEM file associated to an idealized part file in Pre/Post

When you work in a concurrent engineering environment, in teams, or with managed data, you generally associate your FEM to an idealized part file. The idealized part file, which is created in Pre/Post, contains a component CAD part file. However, if you are working with imported, nonstructural, or generalized geometry, you can associate the FEM file directly to the part.

Non-associative FEM files

A non-associative FEM file has the following characteristics:

• It is not associated with the CAD part (.prt) file.

• It contains no polygon geometry.

• It may contain imported mesh data (for example, from .unv or .dat files).

• It may contain non-geometry-based nodes and elements that are created manually.

Non-associative FEM files are appropriate for certain specialized applications. However, a typical analysis using Pre/Post is based on existing CAD geometry. Most of the CAE models you define will use associative FEM files.

A non-associative FEM containing imported mesh data

Learn more

CAE model files

Simulation file

FEM file

Idealized part file

Assembly FEM file

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Associative and non-associative FEM files, Simcenter 3D 2021.1 Series

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