Hole-Drilling Residual Stress Measurement in an Intermediate Thickness Specimen

Abstract

The hole-drilling method for measuring residual stresses is generally applied to two extreme cases. In the “thick” case, the specimen depth is large compared with the hole depth; its far boundary is sufficiently distant to have negligible effect on the deformations around the hole. In the “thin” case, the specimen has the form of a thin plate with a through hole for which the classical Kirsch solution applies. This research focuses on the intermediate case where the specimen has a thickness a small multiple of the hole depth. The far boundary is then near enough to have significant influence. The unsymmetrical geometry of a blind hole in a finite thickness plate creates significant bending deformations that are not present in either extreme case. The intermediate case is investigated here using finite element analysis and also using an analytical model. Based on the finite-element results, the analytical model is empirically adapted to include the effects of localized deformations around the hole. This development allows a user to make practical measurements in intermediate thickness plates without having to do custom finite element analysis or require extensive tables of empirical results.