Prediction of Central Burst in Forward Extrusion Using Continuum Damage Mechanics

The Continuum Damage Mechanics is a branch of applied mechanics that predicts the initiation of cracks in metal forming processes. In this paper, a modified ductile damage model is applied to predict initiation of the micro-void as a central burst along the bar axis during the forward extrusion. The implicit integration scheme of the coupled constitutive equations is presented. The effects of various process parameters including die semi-angle, reduction in area, friction coefficient and material ductility on central bursts are discussed. To verify the quality of simulations, numerical predictions were compared with published experimental results, and good agreement was observed.