Shear band broadening in simulated glasses

A model for shear band width as a function of applied strain is proposed that describes shear bands as pulled fronts which propagate into an unsteady state. The evolving structural state of material ahead of and behind the front is defined according to effective temperature shear-transformation-zone theory. The model is compared to another that is based on dimensional analysis and assumes shear band dynamics is governed by the strain rate within the shear band. These models are evaluated on three material systems: a two-dimensional binary Lennard-Jones glass, a Cu64Zr36 glass modeled using an embedded atom method potential, and a Si glass modeled using the Stillinger-Weber potential. Shear bands form in all systems across a variety of quench rates and appear to either broaden to the system size or saturate to a finite width, remaining contained within the simulation cell. The dimensional analysis-based model appears to apply only when band growth is uncontained, indicating the dominance of a single timescale in the early stages of shear band development. The front propagation model, which reduces to the dimensional analysis model, applies to both contained and uncontained band growth. This result suggests that competition between the rate of shear-induced configurational disordering and thermal relaxation sets a maximum width for shear bands in a variety of material systems.