In situ monitoring of plastic deformation using ultrasound

TL;DR

This paper demonstrates that ultrasound can be used to monitor plastic deformation in aluminum by measuring shear wave speed changes, providing a non-destructive, real-time method to assess dislocation activity during stress application.

Contribution

It introduces a novel application of ultrasound for in situ monitoring of ductile failure, linking shear wave speed variations to dislocation density during deformation.

Findings

Shear wave speed decreases at the yield point.

Ultrasound measurements correlate with dislocation proliferation.

Provides a continuous, quantitative relation between stress and dislocation density.

Abstract

Ultrasound has long been used as a non-destructive tool to test for the brittle fracture of materials. Could it be used as a similar tool to test for ductile failure? This study reports results of local measurements of the speed of shear waves, $v_T$, in aluminum under standard testing conditions at two different locations on the same sample, as a function of stress. There is a clear change in $v_T$ at the Yield stress, consistent with a proliferation of dislocations. This measurement provides a quantitative, continuous relation between dislocation density and externally applied stress.