Thawed Matrix method for computing Local Mechanical Properties of Amorphous Solids

TL;DR

This paper introduces a new method called Thawed Matrix for accurately computing local mechanical properties in amorphous solids by suppressing external plastic rearrangements, improving predictions of plastic activity.

Contribution

The method enhances the frozen matrix approach by reducing artifacts and better correlating local structure with plastic rearrangements in amorphous solids.

Findings

Localization of plastic deformation with increasing field strength

Improved prediction of plastic rearrangements from structural data

Reduced artifacts compared to previous methods

Abstract

We present a method for computing locally varying nonlinear mechanical properties in particle simulations of amorphous solids. Plastic rearrangements outside a probed region are suppressed by introducing an external field that directly penalizes large nonaffine displacements. With increasing strength of the field, plastic deformation can be localized. We characterize the distribution of local plastic yield stresses (residual local stresses to instability) with our approach, and assess the correlation of their spatial maps with plastic activity in a model two-dimensional amorphous solid. Our approach reduces artefacts inherent in a previous method known as the "frozen matrix" approach that enforces fully affine deformation, and improves the prediction of plastic rearrangements from structural information.