Microscopic Mechanism of Shear Bands in Amorphous Solids

TL;DR

This paper uncovers the microscopic mechanism behind shear band formation in amorphous solids, revealing that correlated Eshelby-like quadrupoles organize plastic flow into shear bands, which is key to understanding and preventing failure in metallic glasses.

Contribution

It provides an analytical explanation for shear localization, showing that aligned quadrupoles form minimum energy shear bands at high strain, advancing the understanding of amorphous solid failure.

Findings

Shear bands form along 45 degrees to compressive stress.

Aligned quadrupoles are minimum energy configurations at high strain.

The mechanism explains shear localization in metallic glasses.

Abstract

The fundamental instability responsible for the shear localization which results in shear bands in amorphous solids remains unknown despite enormous amount of research, both experimental and theoretical. As this is the main mechanism for the failure of metallic glasses, understanding the instability is invaluable in finding how to stabilize such materials against the tendency to shear localize. In this Letter we explain the mechanism for shear localization under shear, which is the appearance of highly correlated lines of Eshelby-like quadrupolar singularities which organize the non-affine plastic flow of the amorphous solid into a shear band. We prove analytically that such highly correlated solutions in which $\C N$ quadrupoles are aligned with equal orientations are minimum energy states when the strain is high enough. The line lies at 45 degrees to the compressive stress.