Shear yielding of amorphous glassy solids: Effect of temperature and strain rate

TL;DR

This study investigates how temperature and strain rate influence shear yielding and flow in glassy materials using molecular dynamics simulations, revealing linear stress reductions with temperature and complex strain rate dependencies.

Contribution

It provides new insights into the temperature and strain rate effects on shear yield stress and flow in amorphous solids, challenging traditional thermal activation models.

Findings

Shear yield stress decreases linearly with temperature.

Steady state flow stress also drops linearly with temperature.

Strain rate dependence is nearly independent of temperature.

Abstract

We study shear yielding and steady state flow of glassy materials with molecular dynamics simulations of two standard models: amorphous polymers and bidisperse Lennard-Jones glasses. For a fixed strain rate, the maximum shear yield stress and the steady state flow stress in simple shear both drop linearly with increasing temperature. The dependence on strain rate can be described by a either a logarithm or a power-law added to a constant. In marked contrast to predictions of traditional thermal activation models, the rate dependence is nearly independent of temperature. The relation to more recent models of plastic deformation and glassy rheology is discussed, and the dynamics of particles and stress in small regions is examined in light of these findings.