All-hexahedral remeshing for the finite element analysis of metal forming processes

Hexahedral elements are computationally efficient for three-dimensional modelling of metal forming processes but its utilization is still below expectations due to significant barriers caused by remeshing. Remeshing of hexahedral meshes is generally time consuming when performed manually or semi-automatically, suffers from lack of robustness when performed automatically and is commonly regarded as the bottleneck of the finite element analysis of metal forming processes. This paper presents an algorithm for the automatic generation of all-hexahedral meshes that is capable of representing the deformed geometry of a workpiece during updated Lagrangian finite element calculations without loosing geometrical as well as mechanical consistency. Topics to be addressed include the extraction of the basic geometrical features of the deformed mesh, construction of the core mesh, generation of the boundary mesh linking the core with the surface of the workpiece, application of smoothing procedures to edges, surfaces and volumes and transfer of field variables from the old to the new mesh. The emphasis is focused on providing detailed description of the algorithms and programming solutions for the benefit of those who want to design similar softwares for supporting their metal forming finite element simulation systems. The effectiveness of the proposed algorithm is discussed through its application to a simple but illustrative example derived from the cylindrical side pressing of a rod. Additional and more complex metal forming examples are included to enrich the presentation and to illustrate its scope of application.