A portable digital speckle pattern interferometry device to measure residual stresses using the hole drilling technique

This paper presents a portable device to measure residual stresses using the hole drilling technique combined with digital speckle pattern interferometry. This device, which is based on only one dual -beam illumination system, allows the determination of the three components of the residual stress from the measured displacement field generated by the hole when specimens are placed outside of the optical bench. The description of the portable device and its principal characteristics is followed by the presentation of some preliminary experimental results obtained in thin aluminium plates subjected to a uniform uniaxial stress. An error analysis of the uncertainty sources introduced during the evaluation of the residual stresses, namely the error generated by the automatic data processing, the error produced by an incorrect location of the hole centre and the introduction of rigid body displacements, is also presented.