(256f) Dynamics of Soft Particle Glasses in Transient and Steady Shear Flow

Soft particle glasses (SPGs), jammed beyond the random close-packing fraction of equivalent hard spheres, exhibit complex rheological behaviors under shear flow. The softness of the particles facilitates their ability to compress beyond the random close-packing of hard spheres and form flat facets at particle contacts. In this regime, thermal energy plays a minor role, and contact forces dominate, governing the morphology and macroscopic rheology. These materials demonstrate yield stress behavior, following the Herschel-Bulkley (HB) relationship in steady shear flow. Understanding the interplay between softness, size distribution, particle volume fraction, and flow strength on the microscopic dynamics and rheology of SPGs is crucial. By employing particle dynamics simulations, we will establish a direct link between microscopic dynamics and macroscopic properties in shear flow. Analyzing shear flow curves and trajectories will help identify domains with heterogeneous motion, allowing us to correlate the length scale of these domains with stress-strain behavior at different shear rates. Additionally, we will distinguish between particle dynamics in transient and steady flows, shedding light on the impact of mechanical history (such as pre-shear direction, rest time, and internal stress magnitude) on SPGs dynamics. This work provides a fundamental understanding of the physics of soft particle glasses, with potential implications in various fields, including materials science, rheology, and industrial processes and enhances our ability to design and manipulate rheology of soft materials with precision and efficiency.