Author(s)

F.M. de Sciarra & L. Rosati

Abstract

Extremum properties of an internal variable formulation in elastoplasticity with nonlinear mixed hardening F.M. de Sciarra, L. Rosati Fe(feHco Tecc/^zo ^0, ^0^5 TVopofz, ABSTRACT An internal variable formulation for a class of elasto-plastic models with non- linear mixed hardening is addressed in the paper. After a backward-difference time integration of the flow rule, a finite-step structural problem is formulated in a geometrically linear range. The related variational formulation is then consis- tently derived on the basis of classical results of convex analysis and of a recently contributed potential theory for monotone multi-valued operators. A convex min- imum principle in terms of stresses, displacements, plastic parameters, plastic and total strains is presented and two saddle functional involving a reduced number of the previous variables are then obtained. INTRODUCTION It is nowadays widely a

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