Critical stress statistics and a fold catastrophe in intermittent crystal plasticity

TL;DR

This paper investigates the initial plastic event in crystal plasticity through dislocation dynamics, revealing how pre-existing configurations determine the stress at which plasticity occurs and identifying the key dislocations involved.

Contribution

It introduces a linear stability analysis approach to link dislocation configurations with the onset of plasticity, highlighting a fold catastrophe mechanism.

Findings

Dislocation configurations directly influence the plastic event stress.

Between one and two dislocations trigger the plastic event.

Irreversible strain correlates with the triggering dislocations.

Abstract

The statistics and origin of the first discrete plastic event in a one dislocation dynamics simulation are studied. This is done via a linear stability analysis of the evolving dislocation configuration up to the onset of irreversible plasticity. It is found, via a fold catastrophe, the dislocation configuration prior to loading directly determines the stress at which the plastic event occurs and that between one and two trigger dislocations are involved. The resulting irreversible plastic strain arising from the instability is found to be highly correlated with these triggering dislocations.