  Recent studies of athermal systems such as dry grains and dense, non-Brownian
suspensions have shown that shear can lead to solidification through the
process of shear jamming in grains and discontinuous shear thickening in
suspensions. The similarities observed between these two distinct phenomena
suggest that the physical processes leading to shear-induced rigidity in
athermal materials are universal. We present a non-equilibrium statistical
mechanics model, which exhibits the phenomenology of these shear-driven
transitions: shear jamming and discontinuous shear thickening in different
regions of the predicted phase diagram. Our analysis identifies the crucial
physical processes underlying shear-driven rigidity transitions, and clarifies
the distinct roles played by shearing forces and the density of grains.
