A DETECTION OF BACKSIDE CRACK USING ROTATIONAL MAGNETIC-FLUX SENSOR WITH SEARCH COILS

We have developed a new magnetic sensor using a rotational magnetic fi eld with a three-axis search coil for non-destructive testing (NDT). U sing specimens with a machined crack in the center, we investigated th e relationship between the position and the depth of a crack and the o utput signal of the three-axis search coil. The results of our experim ents, this sensor can clearly detect a crack existing on the reverse s ide of the sensing surface. In this paper, we present the construction , results of numerical analysis and experimental results of this senso r.