Uncertainty analysis of displacements measured by phase-shifting Moire interferometry

摘要

Phase-shifting Moire interferometry is a whole-field optical technique used to measure displacements. Because of its high sensitivity, its results are affected by even small environmental perturbations. In this paper, the influences of these perturbations are characterized and compared with other systematic effects. The experiment was a uniaxial tensile test. In-plane displacement measurements were performed several times under repeatability conditions at different load stages. The dispersions of these results were evaluated by their standard deviations, which showed fluctuations at twice the fringe frequency. An uncertainty analysis was carried out to include other systematic effects. We found that the local displacement uncertainties depended on the sample elongation and on the reference location. An equation was found for these uncertainties as a function of the total number of fringes occurring.