Finite element simulation of the shearing mechanism in the blanking of sheet metal

Numerical simulation of the blanking process of a sheet metal, i.e. the formation of roll-over and a burnished surface, and crack initiation and propagation, is done using a rigid–plastic finite element code developed by the authors. The modified Cockcroft and Latham expression is used as a ductile fracture criterion and is linked with the simulation. It is assumed that when the ductile fracture threshold is satisfied at an element, a crack occurs and propagates through the element. The node separate method is proposed as a method for simulating the crack propagation. To confirm the results of finite element simulation, blanking experiments are also carried out using a steel sheet of 3 mm thickness under various clearances between the punch and the die, and the crack propagation with punch penetration and the shape of the sheared edge are observed. These experimental results show good agreement with those of the finite element simulation.