Rail defect inspection using alternating current excitation coils with digital demodulation algorithm

Rail defect inspection using alternating current excitation coils is introduced in this paper. By using different kinds of coils, rail inspection sensors are designed with optimizing method. In order to find out the optimized coil structure and the excitation frequency, electromagnetic finite element method is used to simulate the performance of the detection sensors. Furthermore, the experiment system has been developed to test the defects in the rail samples. In this experimental system, digital demodulation algorithms are used to extract the influence of defects on the excitation and measurement coils. Then the defects in the rail samples can be calculated.