Plastic response of a 2D amorphous solid to quasi-static shear : I - Transverse particle diffusion and phenomenology of dissipative events

TL;DR

This study uses simulations to analyze how a 2D amorphous solid responds to shear, revealing diffusive non-affine motion, correlations of plastic events, and proposing a phenomenological model involving elastic loading and localized transformations.

Contribution

It introduces a detailed analysis of non-affine displacements and proposes a phenomenology of plasticity based on elastic interactions and shear transformation zones in amorphous solids.

Findings

Non-affine motion is diffusive with size-dependent diffusion constant.

Plastic events are correlated and involve localized shear transformations.

A phenomenological model of plasticity involving elastic loading and flips is proposed.

Abstract

We perform extensive simulations of a 2D LJ glass subjected to quasi-static shear deformation at T=0. We analyze the distribution of non-affine displacements in terms of contributions of plastic, irreversible events, and elastic, reversible motions. From this, we extract information about correlations between plastic events and about the elastic non-affine noise. Moreover, we find that non-affine motion is essentially diffusive, with a clearly size-dependent diffusion constant. These results, supplemented by close inspection of the evolving patterns of the non-affine tangent displacement field, lead us to propose a phenomenology of plasticity in such amorphous media. It can be schematized in terms of elastic loading and irreversible flips of small, randomly located shear transformation zones, elastically coupled via their quadrupolar fields.