A mixed elastoplastic/rigid-plastic material model

In forming process simulations, the rigid{plastic material model is widely used because of its numerically robust behaviour. The model yields accurate results, as long as the strain increments are large compared to the elastic limit strain. In cases where the strain increments are small e.g. in dead metal zones or in case of elastic spring back the model is unstable or inaccurate. In this paper a new integration algorithm is described for large strain plastic deformations. The algorithm degenerates to the Euler forward elastoplastic model for small strain increments and to the rigid{plastic model for large strain increments. The model bene ts from the advantages of both models: accuracy and fast convergence over a large range of strain increments. The applicability of the method to forming process simulations is demonstrated by several examples