Determination of Biaxial Residual Stresses by a Holographic-Hole Drilling Technique

A technique is described for the rapid determination of residual stresses through the combined use of hole drilling and holographic interferometry. A small diameter blind hole is drilled into a part containing residual stresses and the displacement field caused by localized stress relief is registered using holographic interferometry instead of a strain gage rosette. The optical interference fringe pattern created in the hologram upon release of stress is analyzed by a fringe counting method that allows stresses to be computed quickly. A comparison of stresses determined by the holographic hole drilling technique with different known biaxial residual stresses is shown.