高铁车轮电磁层析成像探伤机理及测试方法研究

The whole wheel of high-speed train is made of rolled steel, which is subject to huge load and frictions in the process of the actual operation and is prone to appear tread abrasion, peeling, crack and other damage. There are some researches of the evolution of the mechanism, distribution and detection of defects in the production and application of high-speed train wheels. These are the major scientific and technical problems in the field of railway production and safety. This project aims to study on the evolution mechanism of defects in high-speed train wheels and its coupling with electromagnetic excitation system，use the method of electromagnetic tomography to scan the superficial defects of wheels, then exploit an online experimental system for defects analysis. In this research, the periodic noise suppression principle and digital phase-locked analysis method for periodic rotating work piece are explored to improve the capability of the weak signal detection of the front-end sensor coil array of the imaging system. This paper also studies the U-shaped sensing structure of on-line detection, the image reconstruction algorithm and the defects extraction prevention of the wheels. The multi-frequency and multi-channel rapid analysis of the detection system is realized by using the FPGA parallel processing technology to meet the requirements for on-line detection of the wheel production line. The test experiments will be carried out in the largest high-speed train wheel production base and high-speed rail depot in the world. It is expected that the research results will improve the non-destructive testing level of high-speed train wheels of production and operation enterprises and enhance the recognition ability of small defects of wheels and ensure the safety of high-speed train operation.

高速列车车轮均为辗钢整体车轮，其在实际运营过程中承载大、摩擦剧烈，易出现踏面的擦伤、剥离、裂纹等损伤。高铁车轮在生产和应用过程中缺陷的产生、发展机理、分布及检测方法研究，是铁路生产与安全领域面临的重大科学技术难题。本项目拟研究高铁车轮缺陷发生演变机理及缺陷与电磁激励系统的耦合作用，应用电磁层析成像分析方法，对高铁车轮进行车轮浅表层缺陷的扫描，研制车轮生产线在线损伤分析实验系统；探索针对周期旋转工件的周期噪声抑制原理及数字锁相分析方法，提高成像系统前端传感线圈阵列的弱信号检测能力；研究应用于车轮的在线检测的U形传感结构、图像重建算法及缺陷提取防范；应用FPGA并行处理技术实现检测系统的多频多通道快速分析，以满足车轮生产线在线检测要求，测试实验将在高铁车轮生产基地和高铁车辆段进行。预期研究结果将改善生产及运营企业高铁车轮无损检测水平，提高车轮微小缺陷的识别能力，保障高铁运行安全。

项目探索了电磁层析成像技术对高铁车轮进行无损检测的机理和方法，通过理论分析、仿真研究和实验测试研制了车轮探伤测试系统，测试系统可对高铁车轮进行表面及浅表层的缺陷扫描，并利用周期旋转工件的周期噪声抑制原理及数字锁相分析方法，对表征缺陷的微弱信号的进行检测，进而通过专门针对车轮探伤设计的缺陷分布图像重建算法和缺陷特征提取方法实现车轮缺陷检测，系统应用并行处理技术实现了检测系统的多频多通道快速分析。实验测试系统包括车轮试样支撑驱动台架、车轮探伤电磁层析成像传感器和图像重建计算机。所研制测试系统使用了专门设计的U型传感器，该传感器的每个检测平面分别包含6、4、6个传感线圈，组成激励检测阵列。测试系统通过激励信号合成单元和前端信号检测单元实现电磁层析成像的电磁投影激励扫略，可应用多种缺陷分布重建算法进行缺陷分析。测试实验表明，所研制的传感系统在实验室条件下可以满足车轮样品基本缺陷检测的要求。测试系统的设计方法及实验研究经验可为电磁层析成像车轮检测进一步现场应用提供理论和技术基础，对高铁车轮无损检测方法研究有重要意义。