Relationships among structure, memory, and flow in sheared disordered materials

How soft materials yield is a question of fundamental interest to material engineers and rheologists alike. Often, we model complex fluids from observations of the bulk response alone. However, it may be possible to predict material response by understanding the constituent particle interactions and their arrangements. This possibility is investigated here via experiments with a custom built Interfacial Stress Rheometer and densely packed monolayers of repulsive particles and simulations of granular and atomic scale systems. The bulk rheology (G’, G’’) is measured while simultaneously tracking the positions of up to 50,000 particles. We quantify particle microstructure using excess entropy. Results reveal a direct relation between excess entropy and energy dissipation, that is insensitive to the nature of interactions among particles. We use this relation to build a physically-informed model that connects rheology to microstructure. Our findings suggest a framework for tailoring the rheological response of disordered materials by tuning microstructural properties.