Determination of residual stresses using hole drilling and digital specklepattern interferometry with automated data analysis

A digital speckle pattern interferometry and hole drilling combined system is developed to determine the magnitude of the residual stress in a aluminu m thin plate subjected to an uniform uniaxial tensile load. Performing auto mated fringe analysis, the optical data contained in the speckle interferog rams are quickly converted into values of residual stress. The evaluation i s carried out through the: measurement of the in-plane displacement field g enerated by the introduction of the small hole. The displacement held is de termined from the calculation of the optical phase distribution by means of a phase shifting method. The magnitude of the residual stress is finally e valuated through a least-squares calculation and compared with the stress v alue applied to the specimen. (C) 2000 Elsevier Science Ltd. All rights res erved.