Percolating Plastic Failure as a Mechanism for Shear Softening in Amorphous Solids

TL;DR

This paper investigates shear softening in amorphous solids, linking it to percolation of plastic failure regions, and introduces a simple two-state model to describe this phenomenon.

Contribution

It reveals the connection between plastic failure percolation and shear softening, and proposes a novel two-state model for characterization.

Findings

Shear softening correlates with percolation of failed regions.

A two-state model effectively describes shear softening behavior.

Plastic flow steady state is associated with a percolation threshold.

Abstract

``Shear softening" refers to the observed reduction in shear modulus when the stress on an amorphous solid is increased beyond the initial linear region. Careful numerical quasi-static simulations reveal an intimate relation between plastic failure and shear softening. The attaintment of the steady-state value of the shear modulus associated with plastic flow is identified with a percolation of the regions that underwent a plastic event. We present an elementary ``two-state" model that interpolates between failed and virgin regions and provides a simple and effective characterization of the shear softening.