中文摘要：

对带粘弹性包覆层管道中纵向模态的传播特性进行了理论分析，对纵向模态尤其是L（0，2）模态的频散和衰减特性进行研究。在带环氧树脂包覆层钢管中进行激励和接收L（0，2）模态的试验研究。在低频范围下，L（0，2）模态随着频率增加，受环氧树脂层的影响也相应增加，衰减也相应增大。结果表明，对于带有粘弹性包覆层的管道，其衰减频散曲线可用作模态选取的理论指导，用于对管道的缺陷检测。

英文摘要：

Propagation characteristics of longitudinal modes in pipes with viscoelastic coatings are analyzed theoretically. Dispersion and attenuation characteristics of longitudinal modes, especially L（0, 2） mode, are studied. Excitation and reception of L（0, 2） mode in a steel pipe coated with epoxy are carried out in the experiment. With increasing frequency, the effect of the layer of epoxy on propagation characteristics and the attenuation of L（0, 2） mode in low frequency range increases. Results show that attenuation dispersion curves can provide theoretical guidance for mode selection when longitudinal modes are used for defect detection in pipes with viscoelastic coatings.