DEVELOPMENT AND EXPERIMENTAL VALIDATION OF THE DEEP HOLE METHOD FOR RESIDUAL-STRESS MEASUREMENT

The development of a deep hole method, based on earlier techniques, fo r measuring the through-thickness distribution of residual stresses is described. The distortion of a reference hole used in the method was interpreted using analytical techniques to determine the residual stre sses present. The accuracy of the method was investigated using a 100 mm deep plastically deformed ferritic steel rectangular bar. The stres ses in the bar were determined by surface strain gauges. The axial res idual stresses through the depth of the bar, measured by the deep hole method, were found to be within +/- 35 MPa of the stresses determined from the strain gauges in the central 80 mm of the bar.