Measurement of In-Plane Residual Stresses Varying With Depth by the Interferometric Strain/Slope Rosette and Incremental Hole-Drilling

Abstract

A new experimental method utilizing the Interferometric Strain/Slope Rosette (ISSR) and incremental hole-drilling is applied to measure in-plane residual stresses which vary with depth. For each depth increment, the ISSR measures three relieved strain components and two relieved slopes at point near the hole edge. Adapting the classical Integral Method to the ISSR, and incorporating a Tikhonov regularization scheme, stabilized residual stress solutions are back-calculated from the measured deformations. This paper describes the measurement principle of the ISSR, the derivation and numerical calculation of the ISSR hole-drilling coefficients, and the methodology used to back-calculate and regularize the residual stress solution. A verification test on a thin-plate with a through-hole, and residual stress measurements performed on a shot-peened Titanium-alloy block, are presented and discussed.