title: The reflection of guided waves from simple dents in pipes.
abstract: Guided elastic waves have been anticipated as a rapid screening technique for pipe inspection. Dents occurring in pipes are a severe problem which may lead to the possibility of pipe failure. A study of the reflection characteristics of guided waves from dents of varying geometrical profile in pipes is investigated through experiments. Dented region is represented by a series of circumferential cross-sections and its geometric parameters are described by axial length and the maximum and minimum outer diameters. Both single and double sided dents are mechanically simulated in hollow aluminum pipes and then experimentally tested by exciting the longitudinal L(0,2) mode. A quantitative parameter, so-called deformation rate relating to the maximum and minimum outer diameters of the dents is defined to evaluate the effect of the extent of the deformation on the reflection. For both types of dents, it is shown that the reflection coefficients of the L(0,2) mode are all approximately a linear function of their respective deformation rates. Mode conversion occurs at the dents and reflections of the F(1,3) mode are identified. The results show that the amplitude of the reflected F(1,3) mode is generally higher when the dent has stronger non-axisymmetric features.
authors.affiliation: State Key Laboratory of Structural Analysis for Industrial Equipment, Dalian University of Technology, Dalian 116024, China.
authors.forename: Shuyi
authors.initials: S
authors.lastname: Ma
authors.affiliation: State Key Laboratory of Structural Analysis for Industrial Equipment, Dalian University of Technology, Dalian 116024, China; The Department of Civil and Environmental Engineering, the University of Illinois at Urbana-Champaign, 205 North Mathews Ave., Urbana, IL 61810-2352, USA. Electronic address: wuzhj@dlut.edu.cn.
authors.forename: Zhanjun
authors.initials: Z
authors.lastname: Wu
authors.affiliation: State Key Laboratory of Structural Analysis for Industrial Equipment, Dalian University of Technology, Dalian 116024, China.
authors.forename: Yishou
authors.initials: Y
authors.lastname: Wang
authors.affiliation: State Key Laboratory of Structural Analysis for Industrial Equipment, Dalian University of Technology, Dalian 116024, China.
authors.forename: Kehai
authors.initials: K
authors.lastname: Liu
keywords: Deformation rate; Dent; Pipe inspection; Ultrasonic guided waves