Investigation on blanking of thick sheet metal using the ductile fracture initiation and propagation criterion

In metal forming processes such as sheet blanking, severe plastic deformation localizes in a narrow shear band near blanking clearance, and ductile fracture occurs at the final stage. Because the combinations of large nonlinear strain localization, displacement discontinuity and ductile fracture brought obstacles to numerical simulation, a ductile fracture initiation criterion model and an elasto-plastic finite element method (FEM) were presented to simulate localized severe plastic deformation. Initiation and propagation of cracks were treated by deletion-and-replacement approach. The distributions and developing trends of effective strain and damage were predicted, the influence of blanking clearance on fracture was discussed, and an experiment was performed to explore the forming mechanism. © Shanghai Jiaotong University and Springer-Verlag Berlin Heidelberg 2012.