Strain analysis by mismatch moire method and grid method using Fourier transform

We have formerly presented a new method of the moire analysis of strain using the Fourier transform. It uses the phase information of the moire fringe brightness. By shifting the Fourier spectrum of the image of deformed grating lines, we obtain the complex moire pattern. Strain distribution is given as the derivatives of the phases of the complex moire fringes. The analysis is completely automated by digital image processing. All of the laborious and subjective procedures required in the conventional analysis such as fringe sign determination, fringe ordering and fringe interpolation are thus eliminated, and objective, fast and accurate analysis can be made.In this paper, we develop the method to a mismatch method and a grid method. We show some applications for analyzing strain distribution by using this method.