LONGITUDINAL MODES IN PIPES
WITH VISCOELASTIC COATINGS

LIU Zenghua  HE Cunfu  WU Bin  WANG Xiuyan

(College of Mechanical Engineering and Applied Electronics Technology, Beijing University of Technology, Beijing 100022 )

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: Viscoelastic coating Pipe Longitudinal mode Dispersion Attenuation

CLC No: TB559 O348.8

国家自然科学基金资助项目(10272007, 60404017). Received 20060514, received in revised form 20061226