关键词: 管道, 频散, 衰减, 粘弹性包覆层, 纵向模态

Abstract: 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.

Key words: Attenuation, Longitudinal mode Dispersion, Pipe, Viscoelastic coating