Integration methods for complex plastic constitutive equations

This paper shows new results concerning the Finite Element computations with complex plastic and viscoplastic constitutive equations. The integration procedure then needs special numerical treatments when a large number of internal variables are present, or for stiff non-linearities. Implicit and explicit integration methods are compared. The general solution proposed can be applied either in plasticity or in viscoplasticity, for isotropic or anisotropic materials. Several options are proposed in the numerical scheme and for the completion step for the semi-implicit scheme. Numerical tests are performed in order to compare the relative performances of the various approaches.