Emergence and persistence of flow inhomogeneities in the yielding and fluidization of dense soft solids

TL;DR

This study investigates how microscopic structural domains influence the formation and persistence of shear bands in dense soft solids under shear, revealing the role of overconstrained regions in stress buildup and flow inhomogeneities.

Contribution

The paper identifies icosahedral packing domains as key structural features controlling shear band formation and persistence in dense soft solids during shear flow.

Findings

Stress overshoot and shear banding are linked to overconstrained domains.

Icosahedral regions facilitate stress accumulation during shear.

Structural reorganization of these domains governs shear band dynamics.

Abstract

The response to shear of the dense soft solids features a stress overshoot and a persistent shear banding before reaching a homogeneously flowing state. In 3D large scale simulations we analyze the time required for the onset of homogeneous flow, the normal stresses and structural signatures at different shear rates and in different flow geometries, finding that the stress overshoot, the shear band formation and its persistence are controlled by the presence of overconstrained microscopic domains in the initially solid samples. Being able to identify such domains in our model by prevalently icosahedrally packed regions, we show that they allow for stress accumulation during the stress overshoot and that their structural reorganization controls the emergence and the persistence of the shear banding.