A maximum reduced dissipation principle for nonassociative plasticity (Q1287011)

Summary: We introduce the concept of reduced plastic dissipation for a perfectly plastic rate-independent material not obeying the associated normality rule and characterized by a strictly convex plastic potential function. A maximum principle is provided and shown to play the role of variational statement for the nonassociative constitutive equations. The Kuhn-Tucker conditions of this principle describe the actual material behaviour as that of a (fictitious) composite material with two plastic constituents, each of which is associative in some suitably enlarged stress and strain spaces. The proposed principle is shown to coincide with the classical one in case of associative plasticity. A simple illustrative example is reported.