Stress-activated constraints in dense suspension rheology

Dispersing small particles in a liquid can produce surprising behaviors when the solids fraction becomes large: rapid shearing drives these systems out of equilibrium and lead to dramatic increases viscosity (shear-thickening) or even solidification (shear jamming). These phenomena occur above characteristic onset stress are forced into frictional contact. Here we show via simulations how this be understood within framework that abstracts details forces acting at particle-particle contacts general stress-activated constraints on relative particle movement. We find focusing just two constraints, affecting sliding rolling contact, reproduce experimentally observed shear thickening behavior quantitatively, despite widely different properties, surface chemistries, suspending fluids. Within parameters such as coefficients friction each viewed proxy for one more physical chemical origin, while parameter magnitudes indicate importance associated constraint. In way, new link is established connects features observable macroscale rheological measurements classes arising from micro- nano-scale properties.