Particle dynamics predicts shear rheology of soft particle glasses

Abstract

Soft particle glasses are amorphous materials made of soft and deformable particles that are jammed above close-packing. They behave like weak solids at rest, but they yield and flow under external mechanical constraints. Although soft particle glasses are widely used in applications, little is known about how the particle softness and microscopic dynamics determine the macroscopic rheology. Here, we use three-dimensional particle dynamic simulations to analyze the dynamical properties of soft particle glasses at different scales. We demonstrate how the dynamics is determined by the persistence time and the magnitude of the fluctuating elastic forces that develop at contact in the flow. The shear-induced diffusion coefficient, the local structural relaxation times, the shear stress, and the normal stress differences are interconnected through simple relationships that allow the prediction of the macroscopic rheology from the microscopic dynamics.