Archives of Acoustics, 45, 3, pp. 385–391, 2020

Effect of Pipe Bends on the Low-Frequency Torsional Guided Wave Propagation

Wenjun WU
Wuhan University of Technology

Junhua WANG
Wuhan University of Technology

Wave motion in pipe bends is much more complicated than that in straight pipes, thereby changing considerably the propagation characteristics of guided waves in pipes with bends. Therefore, a better understanding of how guided waves propagate in pipe bends is essential for inspecting pipelines with bends. The interaction between a pipe bend and the most used non-dispersive torsional mode at low frequency in a small-bore pipe is studied in this paper. Experiments are conducted on a magnetostrictive system, and it is observed that T(0,1) bend reflections and mode conversions from T(0,1) to F(1,1) and F(2,1) occur in the pipe bend. The magnitude of the T(0,1) bend reflections increases with increasing propagation distance and excitation frequency. The amplitude of the mode-converted signals also increases with increasing propagation distance, but it decreases with increasing excitation frequency. Because of their longer bent path, the test signals for a pipe bend with a bending angle of 180X are much more complicated than those for one with a bending angle of 90X. Therefore, it is even more difficult to scan a bent pipe with a large bending angle. The present findings provide some insights into how guided waves behave in pipe bends, and they generalize the application of guided-wave inspection in pipelines.
Keywords: guided wave; torsional mode; pipe bends; mode conversion
Full Text: PDF


Bao X.L., Raju P.K., Uberall H. (1999), Circumferential waves on an immersed, fluid-filled elastic cylindrical shell, Journal of the Acoustical Society of America, 105(5): 2704–2709, doi: 10.1121/1.426887.

Demma A., Cawley P., Lowe M.J.S., Pavlakovic B. (2005), The effect of bends on the propagation of guided waves in pipes, Journal of Pressure Vessel Technology, 127(3): 328–335, doi: 10.1115/1.1990211.

Demma A., Cawley P., Lowe M.J.S. (2001), Mode conversion of longitudinal and torsional guided modes due to pipe bends, AIP Conference Proceedings, 557(1): 172–179, doi: 10.1063/1.1373756.

Hayashi T., Kawashima K., Sun Z.Q., Rose J.L. (2005), Guided wave propagation mechanics across a pipe elbow, Journal of Pressure Vessel Technology, 127(3): 322–327, doi: 10.1115/1.1990210.

He C., Wu B., Fan J. (2001), Advances in ultrasonic cylindrical guided waves techniques and their applications [in Chinese], Advances in Mechanics, 31(2): 203–214.

Loveday P.W, Long C.S., Ramatlo D.A. (2018), Mode repulsion of ultrasonic guided waves in rails, Ultrasonics, 84: 341–349, doi: 10.1016/j.ultras.2017.11.014.

Maze G., Léon F., Ripoche J., Überall H. (1999), Repulsion phenomena in the phase-velocity dispersion curves of circumferential waves on elastic cylindrical shells, Journal of the Acoustical Society of America, 105(3): 1695–1701, doi: 10.1121/1.426708.

Nishino H., Yoshida K., Cho H., Takemoto M. (2006), Propagation phenomena of wideband guided waves in a bended pipe, Ultrasonics, 44: 1139–1143, doi: 10.1016/j.ultras.2006.05.155.

Rose J.L. (1999), Ultrasonic waves in solid media, Cambridge: Cambridge University Press.

Sanderson R.M., Hutchins D.A., Billson D.R., Mudge P. J. (2013), The investigation of guided wave propagation around a pipe bend using an analytical modeling approach, Journal of the Acoustical Society of America, 133(3): 1404–1414, doi: 10.1121/1.4790349.

Ta D., Liu Z., He P. (2004), Optimal parameters of ultrasonic guided waves non-destructive testing in viscous liquid-filled elastic pipes [in Chinese], Acta Acustica, 29(2):104–110.

Treyssède F. (2008), Elastic waves in helical waveguides, Wave Motion, 45(4): 457–470, doi: 10.1016/j.wavemoti.2007.09.004.

Überall H., Hosten B., Deschamps M., Gerard A. (1994), Repulsion of phase-velocity dispersion curves and the nature of plate vibrations, Journal of the Acoustical Society of America, 96(2): 908–917, doi: 10.1121/1.411434.

Verma B., Mishra T.K., Balasubramaniam K., Rajagopal P. (2014), Interaction of low-frequency axisymmetric ultrasonic guided waves with bends in pipes of arbitrary bend angle and general bend radius, Ultrasonics, 54(3): 801–808, doi: 10.1016/j.ultras.2013.10.007.

Wu W., Wang Y. (2019), A simplified dispersion compensation algorithm for the interpretation of guided wave signals, ASME, Journal of Pressure Vessel Technology, 141(2): 021204, doi: 10.1115/1.4042595.

Zhou W J, Ichchou M N. (2010), Wave propagation in mechanical waveguide with curved members using wave finite element solution, Computer Methods in Applied Mechanics and Engineering, 199(33–36): 2099–2109, doi: 10.1016/j.cma.2010.03.006.

DOI: 10.24425/aoa.2020.134055

Copyright © Polish Academy of Sciences & Institute of Fundamental Technological Research (IPPT PAN)