Reversible plastic events during oscillatory deformation of amorphous solids

TL;DR

This study uses molecular dynamics simulations to explore how amorphous solids respond to oscillatory shear, revealing reversible particle rearrangements, collective behaviors, and the transition to irreversible deformation near the yield point.

Contribution

It uncovers the nature of reversible and irreversible nonaffine particle displacements during oscillatory shear in amorphous solids, highlighting collective clustering near the yield strain.

Findings

Reversible nonaffine displacements follow a power-law distribution.

Large displacements tend to form system-sized clusters near yield.

Irreversible displacements increase with strain amplitude, causing structural relaxation.

Abstract

The effect of oscillatory shear strain on nonaffine rearrangements of individual particles in a three-dimensional binary glass is investigated using molecular dynamics simulations. The amorphous material is represented by the Kob-Andersen mixture at the temperature well below the glass transition. We find that during periodic shear deformation of the material, some particles undergo reversible nonaffine displacements with amplitudes that are approximately power-law distributed. Our simulations show that particles with large amplitudes of nonaffine displacement exhibit a collective behavior; namely, they tend to aggregate into relatively compact clusters that become comparable with the system size near the yield strain. Along with reversible displacements there exist a number of irreversible ones. With increasing strain amplitude, the probability of irreversible displacements during one cycle increases, which leads to permanent structural relaxation of the material.