A VELOCITY APPROACH TO ELASTOPLASTIC AND ELASTOVISCOPLASTIC CALCULATION BY THE FINITE-ELEMENT METHOD

A second order scheme for the time discretization of the elasto-plastic or elastoviscoplastic behavior is proposed, based on a velocity approach. The complete set of equations is given for the evolution problem in the case of small rotations approximation. The method is quite general and may be applied to a large class of constitutive equations. The finite element discretization is briefly outlined and it is shown that the procedure is quite similar to that of previous displacement formulations. A numerical example concerning the sheet metal forming process, with an elasto-viscoplastic behavior and a membrane approximation, is presented. The numerical tests show a considerable improvement in accuracy for a given increment of time. © 1990 by ASME.