抄録
A new digital moire method of circular and radial gratings for measuring in-plane displacement and strain distributions in the polar coordinate system is proposed. A coordinate-transform technique is introduced which enables the image processing to analyze moire fringes generated by circular and radial gratings. The four steps phase-shifting technique is easily achieved by precisely shifting the computer-generated reference gratings. Basic procedures of in-plane displacement analysis are explained in detail. Two experiments of different crack models for large deformation analysis on cracked rubber sheets are shown. Using a deformed grating, the distributions of in-plane displacements are measured and the distributions of strains can be calculated. And results of the application show that the present method is an efficient method in measurement of soft materials which can endure large deformation.
