Research on effect of measured curvature on eddy current evaluation by finite element analysis

Presently, eddy current evaluation has been used in many engineering fields, such as flaw or cracks testing, distance measurement, and material properties measurement. However, eddy current testing is sensitive to multiple parameters, e.g. the sensor lift-off, and the measured curvature, the electromagnetic properties of measured. In this paper, the finite element model of sensor under spheroid and cylinder are built firstly. Then the finite element formulation of coil impedance is carried out. Finally, the effect of the measured curvature on the planar coil impedance, the electromagnetic field distribution of sensor, the eddy current distribution in measured are investigated by finite element analysis, respectively. The conclusions are shown that (1) whenever the measured is convex or concave, the effect trend of measured curvature is almost the same under the nonmagnetic measured; (2) the influence of the measured curvature is different when the measured is magnetic. Therefore, it is necessary to take different measures to correct the curvature effects on different measured.