A quantitative model for the Frank-Read dislocation source based on pinned mean curvature flow

TL;DR

This paper presents a simple, physics-based quantitative model for the Frank-Read dislocation source, accurately predicting its shape and behavior using minimal parameters, and introduces novel simulation algorithms.

Contribution

It introduces a new, physically grounded model for the Frank-Read source based on line tension and pinning, with a complete discretisation and simulation approach.

Findings

Model accurately predicts shape and properties of the Frank-Read source

Only one dimensionless parameter controls the source dynamics

Derived an emergent law relating dislocation length to shear energy

Abstract

This work introduces a simple quantitative model for the Frank--Read source, considered to be one of the most important micro-mechanical mechanisms of dislocation creation in crystalline materials. It has long been known that these sources create dislocations in a repetitive, oscillatory process, which is driven by an external shear force. Unlike the existing explanations in the literature, the model introduced in the present article is based on just a few simple physical principles, namely line tension and dislocation motion due to a single slip plane flow rule, together with a pinning constraint on the ends of the central dislocation line. A complete discretisation, including suitable re-meshing and ``topological cutting'' algorithms, is described and simulation results are discussed. Despite its conceptual simplicity, the model and discretisation described in the present work yield remarkably accurate predictions about the shape and properties of the Frank--Read source. In particular, it is shown that only one dimensionless parameter controls the dynamics of the Frank--Read source if one neglects crystal anisotropy. This allows to derive an emergent law about the length of dislocation line generated per shear energy.