Adaptation of CAD model topology for finite element analysis

The preparation of a Finite Element Analysis (FEA) model from a Computer Aided Design (CAD) model is still a difficult task since its Boundary Representation (B-Rep) is often composed of a large number of faces, some of which may be narrow or feature short edges that are smaller than the desired FE size (for mesh generation). Consequently, these faces and edges are considered as geometric artefacts that are irrelevant for the automatic mesh generation process. Such inconsistencies often cause either poorly-shaped elements or meshes that are locally over-densified. These inconsistencies not only slow down the solver (using too many elements) but. also produce poor or inappropriate simulation results. In this context, we propose a "Mesh Constraint Topology" (MCT) model with automatic adaptation operators aimed at transforming a CAD model boundary decomposition into a FE model, featuring only mesh-relevant faces, edges and vertices, i.e., an explicit data model that is intrinsically adapted to the meshing process. We provide a set of criteria that can be used to transform CAD model boundary topology using MCT transformations, i.e., edge deletion, vertex deletion, edge collapsing, and merging of vertices. The proposed simplification criteria take into account a size map, a discretization error threshold and boundary conditions. Applications and results are presented through the adaptation of CAD models using the proposed simplification criteria. (c) 2007 Elsevier Ltd. All rights reserved.