钢轨中超声导波激励响应计算方法研究

Study on the computation method for the response of ultrasonic guided waves in the rail under sinusoidal excitation

为了在钢轨中激励出特定模态的导波信号,需确定导波发射探头在钢轨上的安装位置和激励方向,导波激励响应计算方法可通过仿真和计算来研究激励位置、激励方向与响应结果的关系,替代传统的试验验证方法。计算时通过半解析有限元方法建立钢轨中超声导波传播的一般均质波动方程,求解方程得到波数和振型矢量,建立钢轨的系统函数模型,在钢轨指定位置和方向施加激励信号,结合傅里叶变换与反变换计算得到最终的激励响应结果。已知激励位置和方向,结合计算结果可以研究分析各导波模态的激励方法。在西宝高速铁路现场试验表明,激励响应计算结果与实际测试结果误差为0.4%,具有较好的一致性。

In order to excite the needed guided wave signal with specific mode in a rail, the mounting position and excitation direction of the ultrasonic guided wave transducer in the rail should be determined. Guided wave excitation response calculation method can be used to study the relationship among the excitation position, excitation direction and response result through simulation and calculation, and replace the traditional repeated test verification methods. Firstly, in the calculation the semi-analytical finite element （SAFE） method is used to establish the homogeneous general wave equation of ultrasonic guided wave, and then the wave numbers, frequencies and eigenvectors are acquired through solving a two-parameter generalized eigenproblem. Finally, the system function model of the rail is established with the wave number and mode shape vector. Combining FFT and iFFT, this model can be used to compute the rail real time final response when an excitation signal is exerted in the defined position and direction. According to the excitation position and direction, combining with the analysis results of stimulation and response, the method for exciting each ultrasonic guided-wave mode can be found. The field experiment was performed in Xi＇ an-Baoji high-speed railway, the experiment results show that the error between the excitation response calculation resuh and the actual measurement result is 0.4% , which means that good consistency is achieved.