Elasto-plastic models of the yielding transition with stress-dependent transition rates

TL;DR

This paper investigates how stress-dependent transition rates in elasto-plastic models influence the critical exponents of the yielding transition in amorphous solids, highlighting the importance of local stress effects on universality.

Contribution

It introduces a modification to standard elasto-plastic models by incorporating stress-dependent transition rates, revealing their impact on critical exponents and the transition's universality.

Findings

Stress dependence alters dynamical critical exponents.

Long-range elastic interactions underpin the stress dependence.

Universality classes may be affected by local stress effects.

Abstract

Elasto-plastic models are among the most successful ways to study the critical properties of the plastic yielding transition of amorphous solids. Typically these models are studied under a condition of constant transition rates from one plastic configuration to another, and in this form they predict the existence of well defined critical exponents that display universality, in the same sense that in standard equilibrium phase transitions. I show however that very naturally the transition rates must not be taken as a constant, but dependent of the local stress excess above the critical value. This modification in the model is seen to affect the values of some of the exponents of the transition, concretely, of the dynamical exponents that are related to the speed at which the system is driven. I argue about the reason for this dependence, claiming that it is due to the quasi-mean field nature of the plastic yielding transition originated in the fact that elastic interactions are long range.