Abstract
Classical finite element analysis (FEA) continues to be a primary computational method of choice for most solid mechanics applications and the explicit method is significantly used in the defense industry for high-speed impact analysis. The explicit lumped-mass approach, without a stiffness matrix, is well suited for rapidly changing/high rate short duration applications, but can produce distinct nuances and severely affect element performances differently than in typical static/implicit methods. In contrast to automatic tetrahedral meshing approaches applied to the entire volume, hexahedral-dominant modeling methods (e.g., [1-3]) attempt to mesh with all hexahedral elements and then automation with other element types is applied only to regions where the Hex mesher has trouble. The methods typically use wedge and/or pyramid elements to transition from hexahedral elements to fill volumes with other types. This results in models that typically have much fewer elements than with “all-Tet” approaches and generally contain the more desirable hex elements in large regions of the mesh. In this paper, the four 2nd order element types depicted in Fig. 1 are used, which authors [4-6] have found to mass lump well for explicit methods and have well-defined contact Fig. 1. 15-node tetrahedron, 19-node pyramid, 21-node wedge, and 27-node hexahedron type finite element topologies used in this paper; serendipity element versions are obtained by omitting the nodes on all faces and at the centroid
