Abstract:  A rail surface crack detection method was proposed based on flexible printed circuit board(FPCB) probe. Through the combination of simulation analyses and high-speed turntable experiments, the detection abilities of probes with different excitation frequencies, different depth defects and cluster dense defects were tested. The test results indicate the optimal excitation frequency suitable for FPCB probe and the applicable detection depth range of defects, and obtain the corresponding relationship between the ability of FPCB square coils which is used to detect dense defects with different spacing and coil size, that is, when the minimum distance between dense defects is known to be X, the side length of the square FPCB coil may be designed to be 2X to basically identify all defects, and the best single-coil detection signals may be obtained if the design is within X, while the best differential detection signals may be obtained within X/2. The conclusions are only applicable to the square coil studied herein.

Key words: differential eddy current, flexible eddy current probe, track defect detection, detection signal processing

摘要： 提出了一种基于柔性印刷电路板（FPCB）探头的铁轨表面裂纹检测方法。通过仿真分析和高速转台实验，对不同激励频率、不同深度缺陷以及簇状密集缺陷的探头检测能力展开测试。根据检测结果分析出适合FPCB探头的最佳激励频率以及适用的检测缺陷深度范围，得出FPCB方形线圈检测不同间距密集缺陷的能力与线圈尺寸的对应关系，即：在已知密集缺陷最小间距为X的情况下，将方形FPCB线圈边长设计为2X即可基本识别出全部缺陷，设计在X以内可获得最佳的单线圈检测信号，设计在X/2以内可获得最佳差分检测信号。此结论仅适用于文中研究的方形线圈。

关键词: 差分涡流, 柔性涡流探头, 轨道缺陷检测, 检测信号处理