Study on planar coil with multi-frequency stimulations applied to an eddy current non-destructive testing

Non-destructive testing (NDT) has preoccupied a growing number of scientists in recent years. In the field of NDT, the eddy current testing is widely used in industry occasions. It is important to optimize the parameters of the planar eddy current coil to improve the sensitivity of non-destructive testing. In this paper, a planar eddy current excitation coil with the multi-frequency signal on a printed circuit board and an array of planar eddy current receive coils were proposed. A simulation model was developed to calculate the parameters of the excitation coil. It is showed that the parameter calculations of the coil by numerical simulation are close to measured value. The coil with multi-frequency could check the cracks simultaneously in different depths of the specimen and enhanced the performance of the eddy current testing system significantly.