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Hole-drilling residual stress measurement in an intermediate thickness specimen Abraham, Colin

Abstract

The hole-drilling method for measuring residual stresses is generally applied to two extreme cases. In the “thick” case, the specimen depth is very large compared with the hole depth. The far boundary is then sufficiently distant that its effect can be neglected. In the “thin” case, the specimen has the form of a thin plate through which the hole penetrates fully. The thin plate creates plane-stress conditions and it is usually assumed that the associated residual stresses are uniform through the plate thickness. This research focuses on the intermediate case where the specimen has a thickness modestly greater than the hole depth. The far boundary is then near enough to give significant influence, and the through-thickness residual stresses are non-uniform. The finite specimen thickness and non-uniform residual stresses create significant bending deformations of the specimen during hole-drilling that are not present in either extreme case. This bending effect creates out-of-plane deformations that can provide an opportunity for a novel measurement approach. The “intermediate” case is investigated using an analytical model and by finite element analysis. Experimental measurements are made using Electronic Speckle Pattern Interferometry (ESPI), and a comparison is made of the theoretical and experimental results.

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Attribution-NonCommercial-NoDerivatives 4.0 International