Advanced holographic nondestructive testing system for residual stress analysis

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 µm 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.

Residual Stress Determination by Hole Drilling Combined with Optical Methods

“…Application of holographic-hole drilling to determine residual stresses from shot peening was described [56]. Near the end of that decade, a portable holographic interferometer was used along with use of small scratches of rectangular or triangular cross section to release stresses [57,58] and create fringes. The purpose of using scratches was to minimize the disruption associated with drilling holes.…”