Role of disorder in finite-amplitude shear of a 2D jammed material

TL;DR

This study compares the responses of 2D jammed solids with varying disorder levels under shear, revealing similar macroscopic behavior but differences in local stiffness and rearrangement likelihood.

Contribution

It demonstrates that disordered and crystalline 2D jammed materials exhibit similar responses at the macroscopic level, with local differences in stiffness and rearrangement propensity.

Findings

Disordered and crystalline materials show similar macroscopic responses.

Crystalline arrangements are stiffer and less prone to rearrangements.

Responses can be described by a common framework regardless of disorder level.

Abstract

A material's response to small but finite deformations can reveal the roots of its response to much larger deformations. Here, we identify commonalities in the responses of 2D soft jammed solids with different amounts of disorder. We cyclically shear the materials while tracking their constituent particles, in experiments that feature a stable population of repeated structural relaxations. Using bidisperse particle sizes creates a more amorphous material, while monodisperse sizes yield a more polycrystalline one. We find that the materials' responses are very similar, both at the macroscopic, mechanical level and in the microscopic motions of individual particles. However, both locally and in bulk, crystalline arrangements of particles are stiffer (greater elastic modulus) and less likely to rearrange. Our work supports the idea of a common description for the responses of a wide array of materials.