基于超声导波的列车转向架结构损伤定位成像研究

Damage Localization Imaging of Train's Bogie Frames Based on Ultrasonic Guided Wave

转向架构架为列车重要部件,其健康状况直接关系到列车安全运行,而基于超声导波的无损检测技术能够用于结构健康监测。采用导波反演法获取构架材料的体波波速,结合Lamb波频散方程得到构架的Lamb波频散曲线,进而选择激励信号。载荷和构架边界都会使响应导波信号特征变得复杂,使得损伤定位误差增加。为减少时域信号误差的影响,采用完好结构与检测结构的激励信号与相应导波能量谱相关系数进行分析。通过此系数获取检测结构的损伤指数,经权函数对各导波传播路径加权,从而得到损伤概率密度大小,进行损伤定位诊断成像。在构架中分别沿焊接方向以及承载剪切方向引入切槽损伤进行实验测试。结果表明,该方法能够较准确地实现损伤定位。

Bogie frame is one of the important components of the train. Its health condition is directly related to the performance of the train. The non-destructive testing technology based on ultrasonic guided waves can be applied to structural health monitoring（SHM）. In this paper, the inverse algorithm was employed to acquire the bulk wave speed of the frame material. The Lamb wave dispersion curves were obtained according to the dispersion equations and used to choose the incident signal. Load and boundary conditions of the frame could generate complex response wave signal, which would increase the error of damage localization. To reduce the effect of time-domain signal error, the energy spectrum correlation coefficients of intact structure response signal and testing structure response signal was introduced in the study. With the use of these coefficients, the damage index of the testing structure could be derived. Then, the transmission path of each guide wave could be weighted through the weighting function. The damage probability density was obtained and used to imaging the position of the damage. As an example, notches along the weld direction and shearing direction were prepared in the bogie frame respectively for the testing. The result shows that the damage position can be located accurately with this method.