Angle of applied shear: a new knob for probing rearrangements in jammed packings

Jammed packings live in complex energy landscapes that can be explored by applying an external strain, for example shear. With repeated cycles of such strain, packings begin to go through the same series of particle rearrangements over and over. However, these cycles and rearrangements have typically been studied using only simple shear, which corresponds to just one possible constant-volume deformation. Here we measure the response of packings to shear applied at all angles. In the limit of linear response, we recover a shear modulus that depends sinusoidally on angle, consistent with [1]. For finite strain, we find that individual rearrangements are surprisingly robust to a change in shear angle, sometimes persisting for nearly 90 degrees.

[1] S Dagois-Bohy, BP Tighe, J Simon, S Henkes, and M Hecke, PRL 109, 095703 (2012).