Thermodynamic dislocation theory: Size effect in torsion

TL;DR

This paper applies thermodynamic dislocation theory to twisted copper wires, successfully modeling size effects in torsion by linking dislocation pile-up to observed torque-twist behavior.

Contribution

It introduces a minimal parameter model that explains size effects in torsion using thermodynamic dislocation theory, aligning well with experimental data.

Findings

Size effect arises from dislocation pile-up.

Model accurately reproduces torque-twist curves.

Parameters are independent of strain rate and temperature.

Abstract

The thermodynamic dislocation theory developed for non-uniform plastic deformations is used here for the analysis of twisted copper wires. With a small set of physical parameters that we expect to be independent of strain rate and temperature, we can simulate the torque-twist curves that match the experimental ones of Liu et al. (2012). It is shown that the size effect results from the accumulation and pile-up of excess dislocations.