Guided waves can be used in pipe inspection over long distances. Presented in this paper is a beam focusing technique to improve the S∕N 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.

Issue Section:
Research Papers
Keywords:
ultrasonic focusing, pipes, ultrasonic materials testing, finite element analysis
Topics:
Pipes, Waves, Finite element methods
1.
Rose
,
J. L.
, 1999,
Ultrasonic Waves in Solid Media
,
Cambridge University Press
, Cambridge.
2.
Alleyne
,
D. N.
, and
Cawley
,
P.
, 1997, “
Long Range Propagation of Lamb Wave in Chemical Plant Pipework
,”
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, and
Dynes
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,”
Proc. SPIE
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3398
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Rose
,
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,
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5.
Li
,
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, and
Rose
,
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Excitation and Propagation of Nonaxisymmetric Guided Waves in a Hollow Cylinder
,”
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0001-4966,
109
(
2
), pp.
457
–
468
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Crossref
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PubMed
 
6.
Li
,
J.
, and
Rose
,
J. L.
, 2001, “
Implementing Guided Wave Mode Control by Use of a Phased Transducer Array
,”
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0885-3010,
48
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3
), pp.
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PubMed
 
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Fink
,
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.
Crossref
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8.
Hayashi
,
T.
, et al., “
Analysis of Felxural Mode Focusing by a Semi-analytical Finite Element Method
,”
J. Acoust. Soc. Am.
0001-4966 (to be published).
9.
Hayashi
,
T.
, and
Endoh
,
S.
, 2000, “
Calculation and Visualization of Lamb Wave Motion
,”
Ultrasonics
0041-624X,
38
, pp.
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–
773
.
Crossref
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PubMed
 
10.
Hayashi
,
T.
, et al., “
Guided Wave Dispersion Curves for a Bar with an Arbitrary Cross-section, a Rod and Rail Example
,”
Ultrasonics
0041-624X (to be published).
Copyright © 2005
 by American Society of Mechanical Engineers
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