Concepts of Cad-integrated Finite Element Analysis

A CAD system contains only part of the information required for structural analysis, namely, geometrical data. In order to generate a finite element model, the CAD geometry needs to be simplified, e.g. by dimensional reduction. Furthermore, information on boundary conditions and loading needs to be supplied. These tasks cannot be performed solely on the basis of a geometrical model, but require engineering expertise. Therefore, direct automatic transition from a CAD model to a finite element model is not feasible. However, finite element analysis can be greatly aided by embedding in a CAD-like environment. Such an integrated FEM software needs to provide three distinct kinds of models: (a) a structural model, composed of the simplified geometry and boundary and loading conditions, as well as load case information; (b) a series of specifically tailored finite element meshes for each of the load cases; (c) a result evaluation model. Furthermore, the finite element analysis itself should provide means of convergence control and adaptivity. We discuss suitable data structures for the three kinds of models, strategies for the construction of these models, efficient algorithms, and practical applications.