Dipole Screening in Pure Shear Strain Protocols of Amorphous Solids

TL;DR

This paper investigates how dipolar charges generated during plastic events in amorphous solids under pure shear strain affect stress redistribution, challenging traditional elastic models and impacting shear-banding predictions.

Contribution

It reveals the presence of dipolar charges during plastic events and their role in screening elastic stress redistribution in amorphous solids.

Findings

Plastic events generate non-uniform strain fields with dipolar charges.

Dipolar screening modifies the stress redistribution from the classical Eshelby kernel.

Implications for modeling shear-banding in amorphous materials.

Abstract

When amorphous solids are subjected to simple or pure strain, they exhibit elastic increase in stress, punctuated by plastic events that become denser (in strain) upon increasing the system size. It is customary to assume in theoretical models that the stress released in each plastic event is redistributed according to the linear Eshelby kernel, causing avalanches of additional stress release. Here we demonstrate that contrary to the uniform affine strain resulting from simple or pure strain, each plastic event is associated with a non-uniform strain that gives rise to a displacement field that contains quadrupolar and dipolar charges that typically screen the linear elastic phenomenology and introduce anomalous length-scales and influence the form of the stress redistribution. An important question that opens up is how to take this into account in elasto-plastic models of shear induced phenomena like shear-banding.