Odd elasticity in driven granular matter

TL;DR

This paper investigates odd elasticity in driven granular materials with ratchet-like friction, demonstrating nonzero odd elastic coefficients and unique properties such as self-healing boundaries and chiral vortices, with implications for active solids.

Contribution

It introduces a time-averaged elasticity theory for driven granular matter with measurable and tunable odd elastic coefficients based on microscopics.

Findings

Nonzero odd elastic coefficients measured via simulations

Presence of self-healing grain boundaries and chiral vortices

Ability to predict and tune odd elasticity from microscopics

Abstract

Odd elasticity describes the unusual elastic response of solids whose stress-strain relationship is not compatible with an elastic potential. Here, we present a study of odd elasticity in a driven granular matter system composed of grains with ratchet-like interparticle friction and activated by oscillatory shear. We find that the system permits a time-averaged elasticity theory featuring nonzero odd elastic coefficients. These coefficients are explicitly measured using molecular dynamics simulations and can be predicted and tuned from microscopics. In the presence of disorder, our driven granular material displays distinctive properties ranging from self-healing grain boundaries in polycrystalline systems to chiral plastic vortices and force chain deflection in amorphous packings. Beyond granular matter, our work motivates the search for microscopic transduction mechanisms that convert periodic nonuniform drive into uniform elastic properties of active solids.