A strategy for repairing geometry

The tools in the Geometry Edit toolset are often used to repair geometry that was imported into Abaqus/CAE. The goals of the repair operations are to create a part with no invalid entities and to create a part that has the smallest number of edges and faces to avoid impacting the mesh generation. If you are unable to create a valid part, you can ignore the invalidity. For more information, see Working with invalid parts. Ideally, the part will have no small edges or faces. You do not have to create a precise part, and you should continue to work with an imprecise part if possible. Parts with imprecise geometry can be meshed. However, in rare cases other operations may fail on parts with imprecise geometry; for example, other meshing functions, adding geometry features, and partitioning. If you cannot work with the imprecise part and you cannot make the part precise, you should return to the CAD application that generated the original file and increase the precision. For more information, see What is a valid and precise part?.

Abaqus/CAE provides many different editing tools, and it is often difficult to decide which of the tools to use and in which order to use them. In general, repairing the geometry of an imported part is an art that requires experimentation and experience. The best approach depends on the complexity of the part and how much detail you want to remain in the part when you mesh the part and analyze it.

The following guidelines will help you develop an efficient approach to repairing your parts:

Use the geometry diagnostic tools

Use the geometry diagnostic tools to query the part for invalid and imprecise entities, free edges, short edges, small faces, and sharp corner angles.

Use selection groups

You can use mouse button 3 to create temporary selection groups to make the combination of geometry diagnostic tools and repair tools easier to use. You can use the geometry diagnostic tools to highlight a region of invalid and imprecise geometry, and you can copy the region into a selection group. You can then paste the selection group into the Geometry Edit toolset when specifying the region to repair.

Use display groups

Use display groups to selectively remove faces and cells to help you see inside complex parts and to determine which entities are highlighted by the geometry diagnostic tools.

Take an incremental approach

Use the repair tools on small groups of selected faces and edges and check that the outcome of the repair process is correct before proceeding.

Keep solids intact

Try not to convert a solid into a shell by removing faces from the solid. To avoid removing faces, use the Replace tool for faces, and the Repair small tools for edges and faces.

Avoid creating wires

If your part is a solid or a shell, try not to perform operations that result in wires. It is difficult for Abaqus/CAE to reconstruct faces from wires.

Remove fillets and chamfers

Use the Replace tool and the Extend neighboring faces option to remove fillets and chamfers from your part and extend the neighboring faces to close the resulting gap.

Remove faces that meet tangentially

Use the Replace tool or the Repair small tool to repair faces that are approximately tangential. You should use the Repair small tool to remove faces that are relatively small. The Repair small tool simply extends the remaining faces until they meet. The small face is deleted in the process, although the result may be imprecise. Use the Replace tool for relatively large faces that meet tangentially. The Replace tool uses underlying points to replace the original faces with an approximate surface.

Check the validity of the part

If your part is invalid, you can check if the repair operations have made the part valid by clicking mouse button 3 on the part in the Model Tree and selecting Update validity from the menu that appears. Checking the validity can be a lengthy operation, and you should wait until you have finished editing the part before you check its validity. If a part is already valid, none of the repair operations will make it invalid.

Create partitions after you repair

If your part contains partitions, the Geometry Edit toolset may delete them during a repair operation. To avoid this problem, you should wait to partition the part until after you have finished editing it.