High-stress regime of a shear-jammed solid: viscoelastic stress response and fracture

Under sufficiently large stresses, initially liquid-like suspensions can be forced into a solid-like state, known as shear jamming. We investigate the experimental conditions which produce fracture in impacted dense cornstarch suspensions. The average shear stresses at which we observe fracture are several orders of magnitude greater than previously reported stresses in similar suspensions, leading us to propose an extension to the existing dense suspension state diagram, to include a new high-stress regime in which shear-jammed solids experience mechanical failure. Within this Fracture regime, the bulk properties of the solidified suspensions (i.e., compressive modulus) do not depend on impact conditions or suspension composition, and the behavior of the soft shear-jammed solids is captured well by a model of an impacted viscoelastic solid.