About the influence of hydrostatic pressure on the yielding and flow of metallic polycrystals

Abstract

We consider an aggregate of single crystals featuring pressure dependent yielding and deviatoric plastic response, and inquire about the overall response of the aggregate. Since this is one of the prototype examples of what is usually called non-associated plastic flow, the investigation is focused upon discerning the essential features of the resulting model at macro-scale: yield surface and flow rule. It is shown that a flow rule relates the macro-direction of plastic deformation, an additional macro-variable (which vanishes in the absence of pressure effects) and the exterior normal of the macro yield surface. Furthermore, if the constituent crystals feature uncoupled volumetric-deviatoric elastic response, then the plastic dilatancy is zero, the equivalent stress function is pressure-independent, and the flow rule reduces to the classical normality rule in the subspace of deviatoric stress tensors. (C) 2014 Elsevier Ltd. All rights reserved.