Electromagnetic-thermal NDT in thin conducting plates

The effectiveness of an electromagnetic-thermal method for non-destructive testing of conductive materials is investigated numerically in thin conductive plates. The detection region is related to the diameter of the exciting coil while the detection period is affected from the crack length and its distance from the coil. Both, the detection range and detection period depend on the crack orientation with respect to the heat flow, the magnetic flux density and the heating time. By proper selection of the coil positions, during a second inspection it is possible to elongate the detection period for the ambiguous cracks and make clear their shape.