[车辆工程与测控]基于增强磁场涡流的高速轨道缺陷检测方法

在高速轨道运输领域中，电涡流检测以其非接触、易实现自动化等特点，被广泛应用于钢轨表面缺陷的检测,然而，由于趋肤效应的存在，涡流检测很难探测出内部伤损。提出了一种增强磁场涡流以抑制趋肤效应的方法：在涡流检测线圈之上增加一个通入直流电流的U形电磁铁，用磁轭导磁到钢轨以增强磁轭下的磁场。通过ANSYS软件进行有限元仿真，分析了增强磁场后涡流渗透深度的改变，同时仿真研究了磁轭的提离和间距对检测效果的影响。搭建了高速轨道检测的实验平台，进行了增强磁场涡流实验，结果表明，适当地增大背景磁场能够使涡流检测到深层次的缺陷并可以提高检测信号的信噪比。

High Speed Track Defect Detection Methods Based on Enhanced Magnetic Field Eddy Currents

In the field of high-speed rail transport, eddy current detections were widely used in the detection of rail surface defects because of non-contact, easy to achieve automation and other characteristics. However, due to the skin effect, it was difficult to detect the internal damages by eddy current testing. A method to enhance the magnetic field eddy currents to suppress the skin effect was proposed: a U-shaped electromagnet with a direct current was added to the eddy current detection coils, and the magnetic yoke was used to conduct magnetism to the steel rail to enhance the magnetic field under the yoke. Through the finite element simulation by ANSYS, the changes of eddy current penetration depths after the enhancement of magnetic field were analyzed. And the influences of yoke lift and distance on the detection effectiveness were simulated. An experimental platform of high-speed track detections was built, and the experiments of enhanced magnetic field eddy currents was carried out. The results show that appropriate background magnetic field enhancement may make eddy current detections have the ability of internal defect detections and improve the signal-to-noise ratio of detection signals.