Paper detail

Direct strain and slope measurement using 2D DSPSI Title

Large variety of optical full-field measurement techniques are being developed and applied to solve mechanical problems. Since each technique possess its own merits, it is important to know the capabilities and limitations of such techniques. Among these optical full-field methods, interferometry techniques take an important place. They are based on illumination with coherent light (laser). In shearing interferometry the difference of the out of-plane displacement in two neighboring object points is directly measured. Since object displacement does not result in interferometry fringes, the method is suited for localization of strain concentrations and is indeed used in industry for this purpose. Used quantitatively DSPSI possesses the advantage over conventional out-of-plane displacement-sensitive interferometry that only a single difference of the unwrapped phase map is required to obtain flexural strains, thereby relieving problems with noise and reduction in the field of view. The first publication on (DSPSI) was made in 1973, but the emergence of a system providing quantitative measurements is more recent. This work aims to present the results of strain measurements using digital speckle pattern shearing interferometry (DSPSI).