The effect of dispersion on long-range inspection using ultrasonic guided waves

The dispersion of ultrasonic guided waves causes wave-packets to spread out in space and time as they propagate through a structure. This limits the resolution that can be obtained in a long-range guided wave inspection system. A technique is presented for quickly predicting the rate of spreading of...

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Bibliographic Details
Published in:NDT & E international : independent nondestructive testing and evaluation 2001, Vol.34 (1), p.1-9
Main Authors: Wilcox, P, Lowe, M, Cawley, P
Format: Article
Language:English
Subjects:
Cross-disciplinary physics: materials science
rheology
Dispersion
Exact sciences and technology
Guided waves
Lamb waves
Long-range testing
Materials science
Materials testing
Nondestructive testing: ultrasonic testing, photoacoustic testing
Physics
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Summary:The dispersion of ultrasonic guided waves causes wave-packets to spread out in space and time as they propagate through a structure. This limits the resolution that can be obtained in a long-range guided wave inspection system. A technique is presented for quickly predicting the rate of spreading of a dispersive wave-packet as it propagates. It is shown that the duration of a wave-packet increases linearly with propagation distance. It is also shown that the duration of a wave-packet after a given propagation distance can be minimised by optimising the input signal. A dimensionless parameter called minimum resolvable distance (MRD) is defined that enables a direct comparison to be made between the resolution attainable at different operating points. Some conclusions are made concerning the resolution of various operating points for the case of Lamb waves in an aluminium plate.
ISSN:0963-8695
1879-1174
DOI:10.1016/S0963-8695(00)00024-4