Advanced holographic nondestructive testing system for residual stress analysis

TL;DR

This paper presents a portable holographic interferometer system for residual stress analysis that uses a new mathematical algorithm and phase-shift compensation to measure stress release around small scratches in metals.

Contribution

It introduces a novel holographic nondestructive testing system with real-time phase-shift compensation and a new calculation algorithm for residual stress measurement.

Findings

Successful stress measurements on aluminum and steel alloys.

Good agreement between theoretical models and experimental data.

Effective real-time analysis of residual stress release.

Abstract

The design and operating of a portable holographic interferometer for residual stress analysis by creating a small scratch along with a new mathematical algorithm of calculations are discussed. Preliminary data of the stress investigations on aluminum and steel alloys have been obtained by the automatic processing of the interference pattern using a notebook computer. A phase-shift compensation technique in real-time reflection interferometry is used to measure the out-of-plane stress release surface displacement surrounding a small scratch (25 um depth and 0.5 mm width) in a plate with residual stress of around 50 MPa. Comparison between theoretical models for a rectangular and triangular shaped scratch with the experimental data are presented.