Yielding and transient shear banding in soft jammed solids

Emanuela del Gado,

Georgetown University, Washington DC, USA

Abstract

The response to shear of dense soft solids often features a stress overshoot and a persistent shear banding before reaching a homogeneously flowing state. By analyzing the time required for the onset of homogeneous flow, the normal stresses and structural signatures at different shear rates and in different flow geometries, we reveal 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. We show that they allow for stress accumulation during the stress overshoot and that their structural reorganization dictates the emergence and the persistence of the shear banding. These findings suggest an intriguing connection between the frozen-in stresses in the initial solid, the self-stress states that develop under deformation and the yielding dynamics, characterized by flow inhomogeneities.

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