Multi-dimensional Integrated Detection of Electromagnetic Acoustic SV Wave and Surface Wave for Steel Rail

The total operating mileage of China's railways is nearly 140 000 km, and a large number of rails have been in service for a long time, which may cause many potential safety hazards. As a non-contact and high penetration detection technology,electromagnetic acoustic can realize the efficient and comprehensive on-line detection of rail. However, due to low energy conversion efficiency, a high-power excitation device is usually needed to drive it to work normally, and the volume and power consumption of single channels are large. Due to the harsh environment, rail needs a high-efficiency and low-cost detection technology that can cover all aspects. Therefore, a multi-dimensional integrated detection method of electromagnetic acoustic shear vertical（SV） wave and surface wave for rail is proposed. Combined with the common characteristics of SV wave and surface wave, a single electromagnetic acoustic meander-line coil was loaded with pulse signals with two different frequencies to generate SV wave and surface wave simultaneously to complete the multi-dimensional detection of railhead surface and rail waist defects. Through the finite element simulation and experiment, it is concluded that the method could simultaneously detect the groove on the railhead surface and the through-hole on the rail waist and separate the two kinds of defect signals by frequency division filtering. The proposed multi-dimensional integrated detection of electromagnetic acoustic SV wave and surface wave could achieve low-cost and high-efficiency detection of rail and eliminate the blind areas of the two ultrasonic detection technologies, to achieve the purpose of complementary advantages.