An Implicit Integration Procedure for Plane Stress J2 Elastoplasticity

A stress integration algorithm for the finite-step elastoplastic constitutive equations of J2 material models under plane stress condition is presented. The procedure is referred to a two-dimensional continuum model consistently derived from the threedimensional one by implicitly fulfilling the constraint enforced by the plane stress condition. A direct exploitation of the property which characterizes the plastically admissible stress as closest-point-projection of the trial elastic state onto the elastic domain is shown to yield a rapidly convergent and robust return mapping algorithm. Iso-error maps illustrate the accuracy of the finite-step constitutive model while the numerical performance of the proposed algorithm is shown by plotting the number of iterations as function of the assigned strain increment.