Quasistatic rheology and the origins of strain

TL;DR

This paper compares rheological laws and microscopic models of granular materials, revealing two distinct regimes based on network stability and fragility, with implications for understanding strain responses.

Contribution

It introduces a new classification of rheological regimes based on stability and fragility of elastoplastic contact networks in granular materials.

Findings

Two rheological regimes identified based on network stability.

Fragility property determines strain response behavior.

Implications for modeling granular material deformation.

Abstract

Features of rheological laws applied to solid-like granular materials are recalled and confronted to microscopic approaches via discrete numerical simulations. We give examples of model systems with very similar equilibrium stress transport properties -- the much-studied force chains and force distribution -- but qualitatively different strain responses to stress increments. Results on the stability of elastoplastic contact networks lead to the definition of two different rheological regimes, according to whether a macroscopic fragility property (propensity to rearrange under arbitrary small stress increments in the thermodynamic limit) applies. Possible consequences are discussed.