Ductile fracture modeling of initiation and propagation in sheet-metal blanking processes

A new ductile fracture initiation criterion and the implement model for simulating automatic crack propagation in sheet-metal blanking processes are presented. Several ductile fracture criteria in shearing mode and their relative accuracy for predicting and quantifying fracture initiation sites in conjunction with experiments and finite element method (FEM) are investigated. The modified model of crack initiation is made to access to the experiments. From the moment of crack initiation to the complete rupture of the sheet, the 2D remeshing procedure in DEFORM combined to deletion-and-replacement method with the maximum circumferential stress criterion is used to predict the direction of crack advancement and updating the explicit geometric description of evolving cracks. Some process parameters, such as clearance between punch and die, influence on the results of sheared and fractured surface shape and size are also studied. The possibility of realizing prediction of many factors that influence shearing quality is indicated.