Convergent polygon bodies

You can create convergent polygon sheet or solid bodies from convergent CAD bodies or from CAD bodies that contain a mix of convergent and analytic geometry.

• Convergent geometry is a faceted representation of geometry in which edges and faces are based on tessellation. Convergent geometry is typically created by reverse engineering processes in which physical objects are scanned and translated into detailed 3D models as polygon facet data, such as STL format data. Additive manufacturing processes, for example, utilize this detailed facet data to both produce and inspect parts.

• Analytic geometry is based on parameterization. Geometry that you create in Modeling is analytic geometry.

• Mixed geometry is composed of both convergent and analytic geometry. When you use feature modeling operations in Modeling to modify convergent geometry, the software creates analytic faces in the convergent body. For example, when you use the Hole command to add a hole feature to a convergent body, the faces on the inside of the hole are analytic faces.

When you create a new FEM file from a CAD part, the software automatically creates either standard or convergent polygon geometry as appropriate for the selected CAD bodies.

• For analytic CAD bodies, Pre/Post creates standard polygon bodies.

• For convergent CAD bodies or for CAD bodies that contain a mix of convergent and analytic geometry, Pre/Post creates convergent polygon bodies.

Creating convergent polygon bodies

For convergent geometry in CAD bodies, the software uses their existing tessellation to create the convergent polygon body; the software does not modify or create any additional facets. Additionally, you cannot modify the facet resolution of convergent polygon bodies. The Polygon Body Resolution option in the New FEM and Edit FEM dialog boxes, as well as the Edit Resolution command are not available for such bodies.

After you create a FEM file that contains convergent polygon bodies, you can use the Edit FEM dialog box to:

• Add additional bodies, including convergent bodies, to the FEM file.

• Remove selected bodies, including convergent bodies, from the FEM file.

Creating convergent bodies from existing polygon bodies

You can also convert existing polygon bodies to convergent polygon bodies. This capability is helpful when you want to make geometry modifications to a polygon body that is not associated to any underlying CAD geometry. For more information, see Converting a polygon body to a CAD convergent-type sheet or solid body.

Preparing convergent bodies for finite element applications

When you import an STL file as a convergent CAD sheet or solid body, the software creates the convergent body as one single, continuous face. To help reduce the time the software needs to create a FEM file on a convergent sheet or solid body and ensure that you can later mesh the convergent polygon body after you create a FEM file, you should:

• When you first import the STL data, always select the Automatic Cleanup check box in the STL Import dialog box. This ensures that the software automatically analyzes and repairs issues with the STL data, such as degenerate facets and folded edges.

• In Modeling, use commands such as Divide Face to subdivide the convergent body into smaller convergent bodies. Splitting a convergent body that contains a single face into multiple faces helps ensure that Pre/Post can generate the corresponding convergent polygon body.

• In Modeling or Pre/Post, use commands such as Split Body to further subdivide the convergent polygon bodies to help facilitate meshing. For the software to mesh a convergent polygon body, the curvature should not be excessively high in any given region, just as with a standard polygon body.Note: As with standard polygon bodies, the software automatically creates Glue Coincident type mesh mating conditions when you use the Split Body command to divide convergent bodies and you select either the Create Mesh Mating Conditions or the Keep Imprinted Edges check boxes in the Split Body dialog box.

Where do I find it?

Application	Pre/PostDesign Simulation
Prerequisite	A CAD part that contains convergent sheet or solid bodies
Simulation Navigator	New FEM

Learn more

Converting a polygon body to a CAD convergent-type sheet or solid body

Associating a polygon body to the CAD convergent-type sheet or solid body

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Related Topics

Generating surface wrap bodies and meshes

Convergent polygon bodies, Simcenter 3D 2021.1 Series

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