Power fluctuations in sheared amorphous materials: A minimal model

The importance of mesoscale fluctuations in flowing amorphous materials is widely accepted, without a clear understanding of their role. We propose a mean-field elastoplastic model that admits both stress and strain-rate fluctuations, and investigate the character of its power distribution under steady shear flow. The model predicts the suppression of negative power fluctuations near the liquid-solid transition; the existence of a fluctuation relation in limiting regimes but its replacement in general by stretched-exponential power-distribution tails; and a crossover between two distinct mechanisms for negative power fluctuations in the liquid and the yielding solid phases. We connect these predictions with recent results from particle-based, numerical microrheological experiments.

Automated summary

The importance of mesoscale fluctuations in flowing amorphous materials is explored in this study. A mean-field elastoplastic model is proposed to investigate the character of power distribution under steady shear flow. The model predicts the suppression of negative power fluctuations near the liquid-solid transition, the existence of a fluctuation relation in limiting regimes, and the replacement of the relation by stretched-exponential power-distribution tails in general. It also uncovers a crossover between two distinct mechanisms for negative power fluctuations in the liquid and the yielding solid phases.