Collective nonaffine displacements in amorphous materials during large-amplitude oscillatory shear

TL;DR

This study uses molecular dynamics simulations to explore how amorphous materials respond to large-amplitude oscillatory shear, revealing initial nonaffine particle displacements and the development of shear bands over cycles.

Contribution

It provides new insights into the microscopic mechanisms of deformation and shear band formation in amorphous solids under cyclic loading.

Findings

Initial nonaffine displacements form disconnected clusters.

Shear stress oscillations decrease after multiple cycles.

Shear bands grow as cycles progress.

Abstract

Using molecular dynamics simulations, we study the transient response of a binary Lennard-Jones glass subjected to periodic shear deformation. The amorphous solid is modelled as the three-dimensional Kob-Andersen binary mixture at a low temperature. The cyclic loading is applied to slowly annealed, quiescent samples, which induces irreversible particle rearrangements at large strain amplitudes, leading to stress-strain hysteresis and a drift of the potential energy towards higher values. We find that the initial response to cyclic shear near the critical strain amplitude involves disconnected clusters of atoms with large nonaffine displacements. In contrast, the amplitude of shear stress oscillations decreases after a certain number of cycles, which is accompanied by the initiation and subsequent growth of a shear band.