Faraday induction effect applied to the detection of defects in a moving plate

This paper presents a new nondestructive testing method. The conductive material being tested moves in a time constant magnetic field. Due to the movement the induced currents in the conductor generate a secondary magnetic field. When the eddy current flow pattern is disturbed by the existence of defects, variations of the magnetic field occur and information about the defects can be assessed by measuring the magnetic field. As far as the authors know this is an original method, which has not yet been reported in the literature, and presents undoubted advantages when the material to be tested is in motion relative to the test sensor (like when inspecting a rail track with a bogie).