Some comments on formulations of anisotropic plasticity

This article compares some recently proposed formulations of phenomenological plasticity in regard to the underlying assumptions about the elastic behaviour and the formulation of the associated flow rule. Specifically, models using an additive split of Lagrangean strain measures and a particular formulation in Eulerian quantities is considered. It is demonstrated that, and made precisely how, the additive Lagrangean strain decomposition implies a particular dependence of the elastic ‘constants’ on the plastic strain. It is further shown in what sense the use of the logarithmic stress rate in a Eulerian formulation is inconsistent with the Hill and Rice notion of ‘normality’.