Effect of Crack Length and Lift-Off Distance on Eddy Current Sensor Array′s Output Characteristics

The basic principles of eddy current array inspecting method were analyzed at first.Then a simulation model of an eddy current array probe was established based on finite element method.The influences of crack length and lift-off distance on output characteristics were analyzed.It was shown that there would be a change on amplitude and phase of output signal when a crack appeared below the footprint of sensing coil in metal structures,and the amplitude and phase of sensing coil was increasing gradually as crack propagation.Besides,there would be a sharp increment of amplitude and phase as lift-off distance increased.The sensor could be applied in crack inspection and distance measurement,but the variation of lift-off distance should be restricted in crack inspecting.