Abstract
The rigid-plastic finite element method is frequently used to predict the deformation behavior of the materials during the forming processes. The constitutive equation employed is usually restricted to a flow-type one so that the normality of the strain rate to the yield surface is entailed. Thus, the deformation cannot follow the abrupt change in stress history. This often yields the overstabilization of the deformation. In this paper, in order to overcome this situation, a rate-type constitutive equation with a one-to-one relation between the stress rate and the strain rate is employed, and the formulation of the rigid-plastic finite element method is presented. The method is applied to the prediction of the flow localization of the strip under tension. The features of the present results are clarified by comparing the results with those due to J2-flow and the corner theory.
