No CAD geometry? No problem for parametric FEA

A parametric FEA program now lets engineers manipulate shapes and positions of features in meshed models without accessing the original CAD model or CAD software ), lets analysts extensively change FEA geometry for designs studies. For instance, cross members on a truck frame might be thickened or thinned for crash studies, or adjusted fore or aft to find a stiffer location. The software also works when CAD models are poorly parameterized. Developers say it needs no CAD license, nor much expertise to use. Most FEA programs link to a CAD system so analysis software cleanly imports geometry by avoiding IGES transfers. If there's a flaw in the design, engineers can quickly adjust the model in the CAD system, and reimport it to the analysis software. But the new capability avoids the necessity of a CAD program. At a recent exhibition, Jean Daniel Beley, one developer of the software with Ansys, showed how several adjustments could be made to a truck frame that exists only as a 20-year old Nastran FEA mesh. He selected elements in a meshed engine cradle by drawing a box around them and indicated in a menu he wanted to move them 110 mm in a particular direction. "No remeshing is needed because the system modifies existing mesh by slightly reshaping some elements," says Beley. "The system tracks misshapen and poor-aspect-ratio elements." Analysis results can include animations of displacements as the selected elements move from one extreme to another, and plots of element quality. The software works on any type of mesh -- structural, CFD, multiphysics, and magnetic. The software also indicates how much reshaping the mesh can take. "It generally depends on element size," says Beley. "Finely meshed models can be reshaped more than coarsely meshed ones." If an adjustment is too severe, and an element gets