一种多层圆管纵向导波频散特性分析方法研究

针对导波频散特性对圆管纵向导波探伤效果影响的问题,提出一种基于频散特性的外推分析方法,通过优化选取导波检测模式和频率来减少频散特性对圆管纵向导波探伤结果的不良影响。首先应用全局矩阵法推导出多层圆管纵向导波的Pochhammer-Chree频散特性方程,并提出一种能够反映纵向导波传播强弱的截面功率流模型。然后结合外推预测和双尺度迭代逼近过程,给出了导波频散特性以及截面功率流的数值计算方法,并利用计算结果进行分析,提出一种导波检测模式和频率的选择方法。实验表明其结果与理论分析基本一致。上述方法可为圆管损伤检测中导波参数的合理选择提供参考。

RESEARCH ON FREQUENCY DISPERSION CHARACTERISTICS OF LONGITUDINAL GUIDED WAVE IN MULTI-LAYER TUBE

An extrapolation analysis method based on dispersion characteristics is proposed to solve the problem caused by the dispersion characteristic of guide wave to the test effect of the longitudinal guided wave in a tube. The negative influence is decreased by initiatively selecting the test mode and frequency of the guided wave. Firstly, the Pochhammer-Chree dispersion equation of the longitudinal guided wave in the multi-layer tube is derived through the global matrix method, and a section power flow model, which reflects the degree of the propagating performance of longitudinal guided wave, is also set up. A numerical implementation method to calculate the dispersion characteristics and the section power flow is developed by combining the extrapolation prediction with the double-scale iterative procedure. A method is presented to select the test mode and frequency of the guided wave based on the analysis of computation results. The experiment shows that the results basically coincide with that of the theoretical analysis. The method is useful to choose reasonably test parameters of the guided wave in a pipeline damage test.