Abstract
There is no lift-off effect on signal amplitude in the newly developed 〓 probe in the eddy current testing. Though fundamental problems of this probe in detecting the crack are investigated, there is no study on application to detect crack growth in the metal materials. In this research, crack extension behavior in the duralumin plates under static and repeated loading conditions are studied by applying the 〓 probe together with the method of caustics. It is shown that the signal amplitude of 〓 probe is increased and the phase angle is delayed as the crack extension velocity is increased under fatigue loading condition.
