Amorphous systems in athermal, quasistatic shear

TLDR

The results should be relevant to understanding plastic deformation in systems such as metallic glasses well below their glass temperature, soft glassy systems (such as dense emulsions), or compressed granular materials. We present results on a series of two‑dimensional atomistic computer simulations of amorphous systems subjected to simple shear in the athermal, quasistatic limit. The plastic events are composed of localized shear transformations that organize into system‑spanning slip lines, and the authors discuss a mechanism for this organization. The simulations reveal that athermal quasistatic shear paths consist of elastic branches punctuated by discrete plastic events whose onset is governed by a quadrupolar mode, and that these events form system‑spanning slip lines whose size scales with system length; moreover, data from three different interaction potentials collapse onto a single curve after rescaling, indicating that the emergent plastic behavior is largely independent of microscopic details.

Abstract

We present results on a series of two-dimensional atomistic computer simulations of amorphous systems subjected to simple shear in the athermal, quasistatic limit. The athermal quasistatic trajectories are shown to separate into smooth, reversible elastic branches which are intermittently broken by discrete catastrophic plastic events. The onset of a typical plastic event is studied with precision, and it is shown that the mode of the system which is responsible for the loss of stability has structure in real space which is consistent with a quadrupolar source acting on an elastic matrix. The plastic events themselves are shown to be composed of localized shear transformations which organize into lines of slip which span the length of the simulation cell, and a mechanism for the organization is discussed. Although within a single event there are strong spatial correlations in the deformation, we find little correlation from one event to the next, and these transient lines of slip are not to be confounded with the persistent regions of localized shear--so-called "shear bands"--found in related studies. The slip lines give rise to particular scalings with system length of various measures of event size. Strikingly, data obtained using three differing interaction potentials can be brought into quantitative agreement after a simple rescaling, emphasizing the insensitivity of the emergent plastic behavior in these disordered systems to the precise details of the underlying interactions. The results should be relevant to understanding plastic deformation in systems such as metallic glasses well below their glass temperature, soft glassy systems (such as dense emulsions), or compressed granular materials.