Finite element analysis of forming limit in bore expanding of aluminium alloy sheets

Summary A recently proposed method to predict the forming limit of sheet metals is applied to the problem of bore expanding. Axisymmetric bore-expanding processes of various aluminium alloy sheets are simulated by the rigid-plastic finite element method. From the calculated histories of stress and strain, the forming limit, i.e. the fracture initiation, is predicted by means of the ductile fracture criterion. The comparison with the experimental results shows that the fracture initiation site and the critical punch stroke are successfully predicted by the present approach. Received 23 February 1998; accepted for publication 12 May 1998