平板和管道周向Lamb波频散和波结构特性

Plate and pipe circumferential Lamb wave dispersion and wave structure characteristics

为指导使用管道周向Lamb波进行缺陷检测的工作,分析并对比研究了弹性平板Lamb波和管道周向Lamb波的频散和波结构特性。在管道周向Lamb波频散方程的推导中引入了修正的传播方向弧长计算以提高频散曲线的计算准确度,这种修正的合理性从两个方面得到证明。计算结果表明,代表管道周向弯曲程度的内、外径之比越大则周向Lamb波的频散和波结构特性越接近于平板,这就为以平板导波研究内、外径之比较大的管道的周向导波的近似处理提供了理论依据。

Circumferential Lamb waves were used for pipe inspections to analyze the dispersion characteristics and displacement distribution along the wall. This paper presents an analysis of the wave structure for elastic plates and pipes using Lamb waves. An algorithm is given to calculate the arc in the propagation direction for the pipe circumferential guided wave formulation that enhances the accuracy of the dispersion curve calculation. The validity is verified in two different ways. The calculational results show that with larger inner to outer radius ratio, the dispersion and wave structure characteristics of the pipe circumferential waveguide more closely resemble those of the plate waveguide, which provides the theoretical basis for the approximation of large radius ratio circumferential guided wave through a plate model.