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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。
In order to guide the detection of defects using the circumferential Lamb waves, the dispersion and the wave structure of Lamb wave and circumferential Lamb wave are analyzed and compared. In the derivation of the Lamb wave dispersion equation in the pipe circumference, a modified calculation of the arc length in the propagation direction is introduced to improve the calculation accuracy of the dispersion curve. The rationality of this correction is proved from two aspects. The calculation results show that the larger the ratio of inner diameter to outer diameter, which represents the degree of circumferential bending, the closer the dispersion and the wave structure of the Lamb wave are to the plate, which is the comparison between the inner and the outer diameter The approximate treatment of large-scale circumferential waveguide provides a theoretical basis.