Guided Wave Focusing Mechanics in Pipe

[+] Author and Article Information
Takahiro Hayashi

Department of Mechanical Engineering,  Nagoya Institute of Technology, Nagoya, Japan

Koichiro Kawashima

 Ultrasonic Materials Diagnosis Laboratory, Nagoya, Japan

Zongqi Sun

 General Electric Global Research Center, Niskayuna, NY

Joseph L. Rose

Department of Engineering Science and Mechanics, The Pennsylvania State University, University Park, PA

J. Pressure Vessel Technol 127(3), 317-321 (Jan 24, 2005) (5 pages) doi:10.1115/1.1990209 History: Received January 14, 2005; Revised January 24, 2005

Guided waves can be used in pipe inspection over long distances. Presented in this paper is a beam focusing technique to improve the SN ratio of the reflection from a tiny defect. Focusing is accomplished by using nonaxisymmetric waveforms and subsequent time delayed superposition at a specific point in a pipe. A semianalytical finite element method is used to present wave structure in the pipe. Focusing potential is also studied with various modes and frequencies.

Copyright © 2005 by American Society of Mechanical Engineers
Topics: Waves , Pipes
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Figure 2

Dispersion curves for longitudinal and flexural modes. (a) Phase velocity; (b) group velocity.

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Figure 3

Dispersion curves for torsional modes. (a) Phase velocity; (b) group velocity.

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Figure 1

Subdescritizations of the semianalytical finite element method for pipes

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Figure 6

Focusing with controlled time delays and amplitudes. Visualization results and circumferential profiles.

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Figure 7

Circumferential profiles for various modes and frequencies showing focusing at 0deg. (a) Shear vertical; (b) longitudinal; (c) shear horizontal.

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Figure 8

Circumferential profiles for various distance showing focusing at 0deg. (a) Shear vertical input at 80kHz; (b) longitudinal input at 50kHz.

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Figure 4

Displacement wave structures for various points in dispersion curves. The left and right images correspond to ones at ωt=0 at ωt=π∕2. (a) L(0,1)50kH; (b) L(0,2)50kHz; (c) F(1,1)20kH; (d) F(1,2)50kHz; (e) T(1,1)50kH; (f) T(1,1)20kHz.

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Figure 5

Focusing with time reversal waves




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