Assessment of distortions in the deep hole technique for measuring residual stresses

The Deep Hole Technique for measuring residual stresses in thick section components is used to determine distributions of residual stresses, through the thickness, of a variety of welded steel components of varying geometric complexity. The technique relies on the measurement of the distortion of a reference hole drilled through the wall thickness. This paper presents recent developments in the analysis of the hole distortion. The measured distortions include diametral changes in the reference hole, together with changes in height during the trepanning of a column containing the reference hole, and are converted to residual stresses using elasticity theory. FE analyses have also been carried out to determine the influence of near surface conditions for thick walled components. These results are then incorporated into the solution procedure.