Problems with CAD models create havoc when building the mesh in FEA software. “There are many aspects of how CAD models can be built that can be a problem to the simula- tion world,” Robertson said. “With finite element analysis, you break the model into literally finite pieces, each with a kind of mapped stiffness. You’re building up this CAD model, break- ing it into a finite element model, and the process of doing that is called meshing, creating a finite element mesh. If you have problematic geometry, that can be a real problem.” With Femap, users employ an array of tools that help to clean
up geometry and help build a finite element model, he noted, and recent Femap releases added more automation to speed up the process. “If you’ve got a lot of thin-wall sections, rather than model them with solid elements, you can actually take the mid- plane and model them with two-dimensional elements—literally squares or triangles—and that really cuts down on the model size, without compromising accuracy,” Robertson added. “To go a stage further, if you’ve got long slender components in the
Biomedical applications employ multiphysics modeling with FEA and CFD software to analyze an entire human cardiovascular system.
model, you can get away with modeling them as one-dimension- al beam elements, rather than many, many solid elements. That process we call idealization, and Femap does that as well.”