Two procedures for out-of-plane displacement calculation in simultaneous shearography images

Abstract

Shearography is an interferometric technique capable of measuring the gradient of the displacement field. Shearography has also been used to determine out-of-plane displacement fields. In the latter case, conventional integration procedures are not the ideal method for determining the displacement field, as they are more susceptible to error propagation. In this work, two integration techniques are presented, the deconvolution technique and a new procedure called analytical integration, both are capable of determining the complete out-of-plane displacement. For the deconvolution technique, an appropriate kernel is proposed to process the sum of two shearography images with orthogonal shear directions. The analytical integration technique makes use of a weighted combination of two shearography images with different shear directions. The proposed techniques were applied to simulated and experimental shearography images obtained in a controlled experiment using a circular aluminum sample. Both techniques showed results with errors lower than 6% compared to the reference displacements.