Efficient conformal tetrahedral finite element mesh generation for moving objects with contact by mesh adaptation

In current product design, CAE based on FEA has become absolutely imperative for developing high quality products. In some analyses of assembly models with movable parts such as electro-magnetic field analyses of motors, conformal tetrahedral meshes including meshes both of objects (parts) and space (called "object mesh" and "space mesh" in this paper) are needed. In general CAE processes, poses of moving parts of CAD models are first modified, then conformal meshes of the modified CAD models are generated, and FEAs are finally performed at each pose of the object in motion. However, simultaneous conformal meshing for objects and spaces is unstable and time-consuming. To reduce the frequency of the meshing, many mesh adaptation methods have been proposed. Although they can generate the conformal mesh of each object pose by modifying the mesh connectivity and vertex positions depending on the object motion, they are inefficient because the mesh topology and geometry are globally adapted even if the differences in poses of the objects in motion are very small In addition, they do not deal with contacts of the object meshes. In this paper, we propose a new efficient tetrahedral mesh adaptation method for moving objects with contact. For efficient mesh adaptation, the mesh adaptation process is applied to only a set of space mesh elements around the moving object based on a distance field. In addition, to keep mesh conformity on the contact regions between object meshes, the topology and geometry of surface triangular meshes of contacted object meshes are adapted by vertex repositioning and local topological operations. The proposed method is demonstrated using three samples. In an experimental result where a cylinder is translated toward a half tube, the conformal tetrahedral meshes with 160k tetrahedra were generated without any inverted elements for about 5 seconds in each motion step.