Bulbul Chakraborty - Emergent Elasticity in Non-Thermal Solids

This talk was part of the Thematic Programme on "Non-equilibrium Processes in Physics and Biology" held at the ESI August 19 -- October 11, 2024.

A collection of non-Brownian particles often form jammed solids if the imposed pressure or shear stress exceeds a threshold.
Examples abound in nature and industry: sand piles, shear-jammed grains, or dense suspensions, and passive and active gels. The solidity of these systems emerges from the imposed stress itself: the rigid structure is created in response to stress and therefore there is no unique zero-stress reference solid network. Often these solids tend to be fragile: living at the edge of rigidity and flow. In order to understand this fragility, we need to understand how rigidity emerges in jammed solids. In this talk, I will present a paradigm for the elastic response of jammed solids that does not emerge from broken symmetry but from local constraints that lead to conservation laws. This type of rigidity has some clear signatures in both their static response (the presence of "force-chains") and in their dynamic response. The latter should describe the yielding and failure of such solids, and I will discuss how this scenario connects to existing frameworks of yielding and failure.