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针对钢轨探伤可靠性试验及缺陷信号采集处理要求,建立了一套基于激光超声技术的无损检测系统。该系统主要包括高能量脉冲激光器、电磁超声换能器、嵌入式信号采集处理系统以及带有人工缺陷裂缝的P60钢轨试件。在分析利用瑞利波探伤机理的基础上,重点研究了激励线圈阻抗匹配方法,介绍了嵌入式信号采集处理系统工作原理及其信号处理过程。最后利用搭建的激光超声检测系统,实现钢轨表面深度不少于0.5mm缺陷的定位,并给出了接收信号幅度与提离距离以及缺陷尺寸的关系。
Aiming at the reliability test of rail flaw detection and signal acquisition and processing requirements, a set of nondestructive testing system based on laser ultrasonic technology was established. The system mainly includes high-energy pulsed laser, electromagnetic ultrasonic transducer, embedded signal acquisition and processing system and P60 rail specimen with artificial defect cracks. Based on the analysis of the Rayleigh wave flaw detection mechanism, the method of impedance matching of the excitation coil is emphatically studied, and the working principle and signal processing of the embedded signal acquisition and processing system are introduced. Finally, the laser ultrasonic testing system was set up to locate the defect whose depth is not less than 0.5mm on the surface of the rail. The relationship between the received signal amplitude and lift-off distance and defect size was given.