Finite Element Analysis of Central Bursting Defects Occurring in Cold Forward Extrusion

An improved approach to simulating the formation of central bursting defects is presented in this paper. The rigid-plastic finite element method and a modified McClintock damage model are employed. An improved node-splitting technique with degenerate element cleaning is proposed. The technique is applied to several cold forward extrusion processes to reveal the effects of reduction of area, die conical angle, and friction on the formation of central bursting defects. A comparison with experimental results and predictions found in the literature shows that the present analysis provides more realistic predictions of the shape of a central bursting defect (i.e., an obtuse V-shape, which is typical).