Initial imperfections and the initiation of wrinkling in finite element modelling of deep drawing

The effect of initial imperfections on the initiation of wrinkling in finit e element models of deep drawing operations is assessed. Models of an annul ar plate are subjected to radial in-plane loading and the effects of differ ent types, magnitudes and distributions of imperfections are investigated. A model of a circular plate subjected to out-of-plane loading from a punch and die is similarly investigated and the results are compared with experim ental data. It is confirmed that initial imperfections are an essential req uirement for the initiation of wrinkling for the case of in-plane loading. Initial imperfections are shown to be unimportant in the initiation of wrin kling for the case of out-of-plane loading.