Prediction of Ductile Fractures Occurrence in Deep Drawing of Square Boxes

Abstract

The authors propose a new approach for the prediction of tearing in the deep drawing process of square boxes. Such an approach is based on a damage mechanics formulation and in particular on the yield condition for damaging materials proposed by Tvergaard and Needleman and on a strain controlled nucleation model. The flow rule associated to the yield condition is introduced in a finite element explicit formulation founded on the solution of the dynamic equilibrium equation and on an explicit time integration scheme. By this way the developed model allows to calculate the void volume fraction value during the deep drawing process of square boxes and consequently to predict the insurgence of tearing by comparing the maximum achieved void volume fraction with the value corresponding to the coalescence of microvoids. The obtained results have been used to construct a particular type of a master curve and their goodness has been confirmed by means of a set of experimental tests.