Volume-shear coupling in a mesoscopic model of amorphous materials

TL;DR

This paper introduces a 2D mesoscopic model for amorphous materials that incorporates volume-shear coupling, revealing effects like altered shear band orientation and deformation stability, relevant for understanding metallic glasses.

Contribution

The model uniquely integrates volume fluctuations with shear, providing new insights into deformation behaviors of amorphous materials.

Findings

Sample volume increases with deformation rate

Shear bands change orientation due to volume-shear coupling

Homogeneous deformation becomes unstable at low rates with strong coupling

Abstract

We present a two-dimensional mesoscopic model of a yield stress material that includes the possibility of local volume fluctuations coupled to shear, in such a way that the shear strength of the material decreases as the local density decreases. The model reproduces a number of effects well known in the phenomenology of this kind of materials. Particularly, we find that: the volume of the sample increases as the deformation rate increases; shear bands are no longer oriented at 45 $^\circ$ with respect to the principal axis of the applied stress (as in the absence of volume-shear coupling); homogeneous deformation becomes unstable at low enough deformation rates if volume-shear coupling is strong enough. We also analyze the implications of this coupling in the context of out of equilibrium shear bands appearing for instance in metallic glasses.