Dislocation avalanches from strain-controlled loading: A discrete dislocation dynamics study

TL;DR

This study uses two-dimensional discrete dislocation dynamics simulations to analyze strain-controlled plastic deformation, revealing how strain rate and system stiffness influence dislocation avalanches and their statistical properties.

Contribution

It provides new insights into strain-controlled dislocation avalanches and their dependence on loading parameters, extending previous stress-controlled studies.

Findings

Dislocation avalanches follow power-law distributions with a cutoff.

Higher strain rates increase average stress at given strains.

Avalanche shapes are temporally asymmetric.

Abstract

We study strain-controlled plastic deformation of crystalline solids via two-dimensional discrete dislocation dynamics simulations. To this end, we characterize the average stress-strain curves as well as the statistical properties of strain bursts and the related stress drops as a function of the imposed strain rate and the stiffness of the specimen-machine system. The dislocation system exhibits strain rate sensitivity such that a larger imposed strain rate results in a higher average stress at a given strain. In the limit of small strain rate and driving spring stiffness, the sizes and durations of the dislocation avalanches are power-law distributed up to a cutoff scale, and exhibit temporally asymmetric average shapes. We discuss the dependence of the results on the driving parameters, and compare our results to those from previous simulations where quasistatic stress-controlled loading was used.