Out-of-equilibrium relaxation of a time-dependent effective temperature

TL;DR

This paper introduces a model for the out-of-equilibrium relaxation of glassy materials using a time-dependent effective temperature, capturing aging, memory effects, and rheological responses.

Contribution

It proposes a novel constitutive framework linking effective temperature dynamics to glassy behavior and rheology in out-of-equilibrium conditions.

Findings

Effective temperature models reproduce aging phenomena.

Memory effects are captured during cooling and reheating.

Steady rheology behavior is explained by the model.

Abstract

Constitutive equations are proposed for the relaxation of a glassy material in contact with a thermal reservoir. The dynamics of a single state variable, identified as an effective temperature accounts for the emergence of glassy behavior at low bath temperature. Memory effect in cooling/reheating experiments are discussed along with several aspects of the response to shear: aging of the response to step strains, response to oscillatory forcing, and steady rheology.