An investigation of the hole-drilling technique for measuring planar residual stress in rectangularly orthotropic materials

The applicability of the semidestructive holedrilling technique to the experimental determination of residual stresses in relatively thin rectangularly orthotropic materials was investigated. From the exploratory work, it was determined that the similitudes, for measurements at a particular ratio of hole depth to diameter, which exist for thick materials are not present in relatively thin materials. This implies that calibration tests must be made for each combination of strain-gage size and plate thickness. As a consolation, however, it was found that there is no need to drill to an optimum depth for thin materials. That is, one may simply drill a small hole completely through the material to obtain the desired strain change.