Computer Modeling of Sheet Metal Forming by the Finite Element Method

Abstract A computer program has been developped for modeling the sheet metal forming, using a large strains, elasto-plastic shell formulation that includes a treatment of friction between punch, die and forming sheet. The model developped is based on a fully shell theory taking Into account as well as membrane effects as bending effects in order to solve Industrial problems where the membrane approach has failed to produce a convergent solution. The analysis is limited in the present paper to bidimensionnal situations as plane strain or axisymmetric drawing or stretching. To take into account of elastic-plastic anisotropic behaviour a special procedure have been formulated to exactly integrate constitutive equations. The unilateral contact and friction conditions are accuratly treated, an Incrementation procedure is used to impose the sliding condition on the punch and the die surface. The model is based on a penalty approach and exactly takes into account the shape of the dies. To illustrate the approachs proposed, numerical examples are given concerning stretching of drawing problems. The results obtained are compared with experiments or with results of the literature, they are in very good agreement. The computer program developped is an efficient tool to solve Industrial problems of sheet metal forming.