Mechanical fluctuations suppress the threshold of soft-glassy solids : the secular drift scenario

TL;DR

This paper introduces a dynamical model explaining how mechanical fluctuations can fluidize soft-glassy materials below their yield stress through secular drift, supported by experiments on granular packings.

Contribution

It presents a novel mechanism combining memory effects and non-linearity to explain fluidization under sub-threshold fluctuations, validated by experimental evidence.

Findings

Mechanical fluctuations induce fluidization below yield stress.

Effective viscous response correlates with small stress modulations.

The secular drift scenario explains long-term accumulation of effects.

Abstract

We propose a dynamical mechanism leading to the fluidization of soft-glassy amorphous mate-rial driven below the yield-stress by external mechanical fluctuations. The model is based on the combination of memory effect and non-linearity, leading to an accumulation of tiny effects over a long-term. We test this scenario on a granular packing driven mechanically below the Coulomb threshold. We bring evidences for an effective viscous response directly related to small stress modulations in agreement with the theoretical prediction of a generic secular drift.