Automatic generation of transitional meshes

Advances in commercial computer-aided design software have made nite element analysis with three- dimensional solid nite elements routinely available. Since these analyses usually con ne themselves to those geometrical objects for which particular CAD systems can produce nite element meshes, expanding the capability of analyses becomes an issue of expanding the capability of generating meshes. This paper presents a method for stitching together two three-dimensional meshes with diverse elements that can include tetrahedral, pentahedral and hexahedral solid nite elements. The stitching produces a mesh that coincides with the edges which already exist on the portion of boundaries that will be joined. Moreover, the transitional mesh does not introduce new edges on these boundaries. Since the boundaries of the regions to be stitched together can have a mixture of triangles and quadrilaterals, tetrahedral and pyramidal elements provide the transitional elements required to honor these constraints. On these boundaries a pyramidal element shares its base face with the quadrilateral faces of hexahedra and pentahedra. Tetrahedral elements share a face with the triangles on the boundary. Tetrahedra populate the remaining interior of the transitional region.