Whole-field strain uncertainty evaluation by a Monte Carlo method

In this work, we used a Monte Carlo computer simulation to evaluate the uncertainties of the strains obtained from a displacement field measured by moire interferometry. The displacements were induced by applying tensile load to a metallic sheet sample. At each point of the illuminated area, the strain standard uncertainty was taken as the standard deviation of the series of outcomes obtained by a large number of strain evaluations. These strain evaluations were performed by differentiating the surfaces that were fitted to the sets of points in the space formed by the two spatial coordinates of the field and the corresponding local displacement. These sets of points were generated according to the probability density functions that we considered appropriate. The reported procedure to evaluate the strain uncertainty is valid independently of the interferometric technique used to measure the displacement field.