Some properties of the dissipative model of strain-gradient plasticity

TL;DR

This paper explores the properties of a dissipative strain-gradient plasticity model, highlighting its global flow relation, computational responses under complex loading, and the elastic gap phenomenon related to boundary conditions.

Contribution

It provides a theoretical and computational analysis of a dissipative strain-gradient plasticity model, emphasizing its flow relation, regularization, and the elastic gap phenomenon.

Findings

Flow relation expressed in terms of Cauchy stress is necessarily global.

The elastic gap occurs with passivation, linking micro-free and micro-hard boundary conditions.

Numerical results illustrate the model's response under non-proportional loading.

Abstract

A theoretical and computational investigation is carried out of a dissipative model of rate-independent strain-gradient plasticity and its regularization. It is shown that the flow relation, when expressed in terms of the Cauchy stress, is necessarily global. The most convenient approach to formulating the flow relation is through the use of a dissipation function. It is shown, however, that the task of obtaining the dual version, in the form of a normality relation, is a complex one. A numerical investigation casts further light on the response using the dissipative theory in situations of non-proportional loading. The elastic gap, a feature reported in recent investigations, is observed in situations in which passivation has been imposed. It is shown computationally that the gap may be regarded as an efficient path between a load-deformation response corresponding to micro-free boundary conditions, and that corresponding to micro-hard boundary conditions, in which plastic strains are set equal to zero.