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由滚动接触疲劳引起的钢轨表面裂纹已成为目前铁路在役钢轨无损检测中的重要问题。在现有铁路钢轨超声检测设备的基础上,可采用超声次表面纵波对钢轨表面裂纹进行检测。本文应用边界元方法(BEM)对钢轨中的次表面纵波的传播特性进行分析并进行了实验测试。通过数值分析,清楚显示了次表面纵波在钢轨头中的传播过程,给出了钢轨头中次表面纵波的主声束指向特性,计算结果表明次表面纵波主声束能量在钢轨头中可波及15~18 mm深度范围,实验测试与数值分析结果基本吻合。本文的研究结果对开发钢轨表面裂纹的超声次表面纵波检测方法具有一定的指导意义。
The rail surface crack caused by the rolling contact fatigue has become an important issue in the non-destructive testing of the existing railway rails. On the basis of the existing railway rail ultrasonic testing equipment, ultrasonic sub-surface longitudinal waves can be used to detect the crack on the rail surface. In this paper, the boundary element method (BEM) is used to analyze the propagation characteristics of the longitudinal waves on the subsurface of the rail and conduct experimental tests. The numerical analysis clearly shows the propagation of the subsurface longitudinal wave in the rail head and the main beam directivity of the sub-surface longitudinal wave in the rail head. The results show that the main beam energy of the sub-surface longitudinal wave can be transmitted in the rail head 15 ~ 18 mm depth range, the experimental test and numerical analysis basically agree. The research results of this paper are of guiding significance for the development of ultrasonic subsurface longitudinal wave detection method for rail surface cracks.