Experimental observations of shear bands
Abstract: When submitted to external stress, granular matter does not flow homogeneously like an ordinary fluid would. Instead, it forms rigid regions separated by narrow shear bands where the material yields and flows. Shear localization is ubiquitous for granular media - think of geological faults, avalanches and silo discharges. Empirically, shear bands are observed to be narrow, particle-shape dependent and often localize near a wall. Here, in contrast, we present experiments in which much wider and universal shear zones can be created in the bulk of the material. These shear zones exhibit Gaussian strain rate profiles, with position and width tunable by the experimental geometry and particle properties.