基于ACFM的钢轨踏面斜裂纹检测系统设计及试验研究

Design and Experiment Research of Oblique Crack Detection System for Rail Tread Based on ACFM Technique

钢轨踏面斜裂纹作为钢轨表面伤损的一种主要表现形式,当其发展到一定深度后会快速扩展导致轨头横向断裂,因此开展钢轨踏面斜裂纹的检测对铁路安全运行意义重大。针对钢轨踏面检测的特点,基于交流电磁场检测技术(Alternating current field measurement,ACFM),开发了一种钢轨踏面斜裂纹检测系统并进行试验测试。利用有限元软件COMSOL,建立钢轨踏面斜裂纹ACFM仿真模型,分析感应电磁场和斜裂纹之间的响应关系,探究不同的扫查路径对特征信号畸变量的影响。设计检测探头、扫查架和检测仪并编写检测软件,形成一套完整的钢轨踏面斜裂纹检测系统,并对不同长度和深度的钢轨踏面裂纹进行检测。仿真和试验结果表明:沿着斜裂纹中心位置扫查路径的特征信号畸变量最小,沿着端点位置扫查路径的特征信号畸变量最大;检测系统可以实现钢轨踏面1 mm深斜裂纹的有效检出;随着裂纹深度的增加,裂纹中心特征信号的畸变量增大,随着裂纹的长度增加,裂纹中心特征信号畸变量先增大后减小。

The oblique crack is the major damage of rail tread surface.When it reaches a certain depth,they will rapidly expand and cause transverse fracture of the rail head.So the detection of oblique cracks on rail treads is of great significance to the railway safe.According to the characteristics of rail tread detection,the rail tread oblique crack detection system is developed and tested based on the alternating current field measurement(ACFM)technique.The ACFM detection model is established by the finite element software COMSOL.The response relationships between the induced electromagnetic field and the oblique cracks are analyzed.And the influences of different scanning paths on the distortion of characteristic signals are explored.The detection probe,scanning frame and detector are designed and the detection software is written to form a complete rail tread oblique crack detection system,and rail tread cracks of different lengths and depths are detected.The simulation and experimental results show that the distortion of the characteristic signal of the center position of the oblique crack is the smallest,and the characteristic signal of the end position is the largest.The detection system can realize the effective detection of the 1mm deep oblique crack on the rail tread.As the depth of the crack increases,the distortion of the crack center characteristic signal increases,and as the length of the crack increases,the distortion of the characteristic signal first increases and then decreases.