Authors: Wen Chiet Cheong,a Heng Keong Kam,b Chan Chin Wang,c Ying Pio Lim
Abstract: In the forging process such as backward extrusion, a workpiece normally undergoes large deformation around the tool corners that causes severe distortion of elements in finite element analysis. Since the distorted elements may induce instability of numerical calculation and divergence of nonlinear solution in finite element analysis, a computational technique of rigid-plastic finite element method by using the Euler’s fixed meshing method is developed to deal with large deformation problem by replacing the conventional way of applying complicated remeshing schemes when using the Lagrange’s elements. With this method, the initial elements are generated to fix into a specified analytical region with particles implanted as markers to form the body of a workpiece. The particles are allowed to flow between the elements after each deformation step to show the deforming pattern of material. The proposed method is found to be effective in simulating complicated material flow inside die cavity which has many sharp edges, and also the extrusion of relatively slender parts like fins. In this paper, four extrusion processes which including backward, forward-backward double cup and axi-symmetric ring cup extrusion are conducted to verify the Euler’s fixed meshing method simulation results. All the results show close agreement.
Keywords: rigid-plastic FEM; euler’s fixed meshing; cold forging; aluminium extrusion