Controlling Strain Bursts and Avalanches at the Nano-to-Micro Scale

TL;DR

This paper uses 3D simulations to show how controlling load or displacement rates can tune the complex dislocation dynamics in nano- and micro-scale crystals, switching between critical avalanches and oscillatory behavior.

Contribution

It demonstrates how external load mode control can qualitatively alter dislocation dynamics, revealing a transition from criticality to quasi-periodic oscillations.

Findings

Strain bursts follow scale-free avalanche statistics under load rate control.

Displacement rate control induces quasi-periodic oscillations in strain response.

External load mode controls the transition between different dislocation dynamics regimes.

Abstract

We demonstrate, through 3-dimensional discrete dislocation dynamics simulations, that the com- plex dynamical response of nano and micro crystals to external constraints can be tuned. Under load rate control, strain bursts are shown to exhibit scale-free avalanche statistics, similar to critical phenomena in many physical systems. For the other extreme of displacement rate control, strain burst response transitions to quasi-periodic oscillations, similar to stick-slip earthquakes. External load mode control is shown to enable a qualitative transition in the complex collective dynamics of dislocations from self-organized criticality to quasi-periodic oscillations.