轨道板中超声兰姆波传播的有限元计算和实验*

该文针对我国高速铁路轨道板缺陷的非接触动态检测问题,研究了空气耦合超声兰姆波在轨道板中的传播规律。首先,给出了轨道板中超声兰姆波的相速度和群速度频散曲线,结果表明:随着频厚积的增加,频散现象越明显,并且A0相速度收敛于Rayleigh波的波速。然后,建立轨道板中波传播的有限元模型,计算得到兰姆波传播的群速度为2220 m/s,且二维傅里叶变换系数的较大值沿Rayleigh波的频散曲线分布。最后,在沪杭高铁嘉兴南站进行了现场测试,以8.8°倾斜角向轨道板激励产生超声兰姆波,激发产生的兰姆波模态群速度为2325 m/s,且二维傅里叶变换分析其系数的较大值沿Rayleigh波的频散曲线分布。有限元计算结果和实验结果均与理论计算结果一致。该研究为后续轨道板缺陷的非接触动态检测提供了理论依据和实验方法。

Finite element calculation and experiment of ultrasonic lamb wave propagation in track slab

In this paper, the propagation of ultrasonic Lamb waves in track plates is studied for the detection of the void defects of high-speed railway track plates in China. Firstly, the phase velocity and group velocity dispersion curves of the ultrasonic Lamb waves in the track plate are calculated. The results show that as the frequency-thickness product increases, the dispersion phenomenon becomes more obvious, and the A0 phase velocity converges to the wave velocity of the Rayleigh waves. Then, the finite element model of wave propagation in the track plate is established. The group velocity of the Lamb wave propagation is calculated to be 2220m/s, and the larger value of the two-dimensional Fourier transform coefficient is distributed along the dispersion curve of the Rayleigh waves. Finally, a field test was carried out at the Jiaxing South Railway Station of Shanghai-Hangzhou High-speed Railway. The ultrasonic Lamb wave was generated by excitation to the track plate at an inclination angle of 8.8°. The group velocity of the Lamb waves generated by the excitation was 2325 m/s, and the two-dimensional Fourier The transformation analyzes the larger value of its coefficients along the dispersion curve of the Rayleigh waves. The finite element calculation results and experimental results are consistent with the theoretical calculation results. This study provides a theoretical basis and experimental method for the non-contact dynamic detection of subsequent track plate void defects.