Nondestructive investigation of wall thinning in layered ferromagnetic material by magnetic adaptive testing

A recently developed nondestructive method, called magnetic adaptive testing, which is based on systematic measurement of minor magnetic hysteresis loops, was applied for detection of local wall thinning in ferromagnetic plates. It was shown that even a relatively small, local modification of the sample thickness could be detected with good signal/noise ratio from the other side of the specimen. The measurements gave good results also, if the investigated plate was covered by other plate(s).