Extension of generalized plasticity to finite deformations and non-linear hardening

The generalized plasticity model\ as presented by Lubliner "0880#\ Lubliner et al[ "0882# and Auricchio et al[ "0881#\ is a generalization of classical rate!independent plasticity with a yield surface[ This material model is able to describe a reloading transient during the reloading process of a specimen\ which is shown in the asymptotic approach of the reloading curve to the initial load curve in the stress strain diagram\ as observed in Lubhahn and Felger "0850# for copper or in Greenstreet et al[ "0860# for graphite[ In the present paper an advantageous extension of the generalized plasticity model to _nite plastic strain regimes is given[ Classical plasticity and the model in Auricchio and Taylor "0884# for linear kinematic and isotropic hardening rules are included as special cases in the proposed concept[ It will be shown that the suggested modi_cation yields a mathematically simple structure of the constitutive relations and an e.cient stress algorithm\ adaptable to _nite element programs similar to that in Auricchio and Taylor "0884#[ Special attention is focused on a correct treatment of the loading criteria