Influence of shearing amount and vibration amplitude on noise in shearography

Abstract

A method for the evaluation of noise in measurements with shearography is reported in this paper. This method is able to quantify the influence of several parameters, namely the shearing amount and the vibration amplitude of rotations, on the measurements accuracy. The method was applied to the first four modal rotation fields of an aluminum beam in free-free conditions, experimentally obtained with an in-house digital shearography system. The root mean squares of noise and the signal-to-noise ratios of these measurements were computed in order to gain insight into the absolute and relative accuracies, respectively. It was found out that the best measurements are obtained with the largest values of the shearing amount and vibration amplitude.