Prediction of sheet forming limits using a new continuum damage mechanics criterion for ductile fracture

Sheet forming is a localization procedure of deformation and damage. In this paper, we firstly give a complete set of constitutive equations for elastic-plasticity coupled with damage. Then, a new continuum damage mechanics based local criterion for ductile fracture, proposed by the author [Engng Fracture Mech. 42, 185-193 (1992)], is presented briefly. Finally, this new criterion is employed to predict the forming limits of sheet. A simple expression for the sheet forming limits prediction is derived, which has practical importance to the selection of forming alloys and the forming technology. Comparisons between the predicted and experimental data are presented and good agreements are found.