Shear localization in 3-Dimensional Amorphous Solids

TL;DR

This paper extends the theory of shear localization from 2D to 3D amorphous solids, revealing a lattice of elastic inclusions responsible for plastic instability, with predictions validated by simulations.

Contribution

The paper introduces a 3D theoretical framework for shear localization, identifying a lattice of elastic inclusions as the instability mechanism, extending prior 2D models.

Findings

A 2D triangular lattice of elementary events forms in 3D shear localization.

The lattice orientation makes a 45-degree angle with the principal stress axis.

The theory's predictions match numerical simulation results very well.

Abstract

In this paper we extend the recent theory of shear-localization in 2-dimensional amorphous solids to 3-D. In 2-D the fundamental instability of shear-localization is related to the appearance of a line of displacement quadrupoles, that makes an angle of 45 degrees with the principal stress axis. In 3-D the fundamental plastic instability is also explained by the formation of a lattice of anisotropic elastic inclusions. In the case of pure external shear stress, we demonstrate that this is a 2-dimensional triangular lattice of similar elementary events. It is shown that this lattice is arranged on a plane, that, similarly to the 2-D case, makes an angle of 45 degrees with respect to the principal stress axis. This solution is energetically favorable only if the external strain exceeds a yield-strain value, which is determined by the strain parameters of the elementary events and the Poisson ratio. The predictions of the theory are compared to numerical simulations and very good agreement is observed.