Three-dimensional automatic mesh generation for remeshing in finite element analysis of metal forming processes

Abstract

The finite method has been a most popular tool to analyze metal forming processes. In the finite element analysis of metal forming processes using general Lagrangian formulation, the nodes in the mesh move as if they were particles in the material. Since metal forming processes usually involve large deformation of the material, mesh degeneracy, the severe distortion of elements in the region of concentrated deformation, is frequently observed. The excessive degeneracy of mesh interrupts finite element analysis by making the determinant of the transformation matrix negative in the finite element calculation. In this case, the degenerated mesh should be discarded and a mesh to replace the degenerated mesh has to be constructed to resume the interrupted analysis. The remeshing procedure allows to construct the new mesh with well-shaped elements and transfers the analysis data from the degenerated old mesh to the reconstructed new mesh. The former operation is called mesh generation and the latter operation is called the transfer of analysis data which consists of the smoothing and mapping of state variables. In this study, the technique of automatic mesh generation during the remeshing procedure has been investigated and some schemes are proposed to develop the effective technique. In order to show the validity and effectiveness of the proposed tehniques, several metal forming processes are simulated using the proposed tehniques. The first technique, master grid approach, constructs fully hexahedral meshes by the grid-based approach. The convention grid-based approach constructs the mesh by superimposing a regular grid over the object to be meshed, then taking internal cells of the grid as the elements, and finally modifying the regged boundary by rearranging nodes. the compulsive projection of the rugged boundary of the mesh onto the surface of the object produces a large number of severely distorted boundary elements. Since the severe deformation is frequently...