Investigation on Crack Tip Strain Field of Welded Joint by Moire Interferometry

A new photo-mechanics method named Moire interferometry of reflected sticking film and its shearing technique are introduced in this paper. The basic principle and its technique are stated also. As an example, the crack tip strain field is measured for an overmetching-weld tension specimen with centre crack of A 537 steel used for offshore platform welded by LB52NS electrode. Because of its high sensityvity(virtual grating frequency is 750lmm) and wide variable measurement scale, the method is more useful for the measurement of honrizontal strain field.