Accurate Measurement of Opening Displacement of Notch with Moiré Interferometry by Changing Applied Load

Abstract

Moiré interferometry is a very sensitive optical method to measure the in-plane displacement of a solid specimen, and is useful to measure small deformation of solids. But, there often appears measurement error caused by the residual strain of the grating that is pasted on a specimen in Moiré interferometry. The present paper applies a method to eliminate the error brought by the residual strain of the grating. The method measures the change of the order of Moiré interference fringes with varying the tensile force applied to the specimen, and obtain the true opening displacement of the notch. The present paper uses the method mentioned above to measure the opening displacement of a bifurcated notch in a plate specimen