Influence of experimental parameters on determination of residual stress using the incremental hole-drilling method

The incremental hole-drilling method is an effective semi-destructive technique for determining the profile and magnitude of residual stresses in composite laminates. This method provides access to the residual stress profile of the intra and inter plies in the through thickness of the laminate. Correct application of the method requires optimisation of the relevant experimental parameters. Tests were performed to investigate the influence of two experimental parameters—the depth of each drilled increment and the influence of the relative position of the strain gages compared with the radius of the hole drilled. The development of a rapid automatic method for numerical calculation of the calibration coefficients enhanced the interest of the method while extending the experimental data range being investigated. The results clearly show that these parameters have an appreciable effect on determination of the residual stress gradient, and especially the magnitude and stability of the residual stress.