A GENERAL ORTHOTROPIC VONMISES PLASTICITY MATERIAL MODEL WITH MIXED HARDENING - MODEL DEFINITION AND IMPLICIT STRESS INTEGRATION PROCEDURE

A general orthotropic von Mises plasticity model, with an extension of the Hill's yield criterion to include mixed hardening, is introduced in the paper. Material constants and equivalent stress-equivalent plas tic strain curves are defined in a way to suggest their experimental d etermination. The model represents a special case of a general anisotr opic metal plasticity model proposed by the authors. An implicit stres s integration procedure, representing an application of the governing parameter method (GPM) introduced by the first author, is presented. T he GPM is briefly described, and the computational procedure, together with calculation of the consistent tangent moduli, are given in some detail for a general three-dimensional deformation, with direction of application to plane stress/shell conditions. Numerical examples illus trate applicability of the model and effectiveness of the computationa l algorithm.