Excitation of single-mode shear-horizontal guided waves and evaluation of their sensitivity to very shallow crack-like defects
Author(s)
Khalili, Pouyan
Cegla, Frederic
Type
Journal Article
Abstract
Inspection is a key part of the asset management process of industrial plants and there are numerous plate-like structures that require inspection. Ultrasonic guided waves have been extensively used to detect various types of defect by monitoring reflected and transmitted signals because they enable faster screening of large areas. However, ultrasonic guided wave testing becomes difficult for very shallow, sharp defects as current inspection techniques suffer from a lack of sensitivity to such features. Previous studies, obtained by comparing various inspection techniques, suggest that the SH1 mode in particular, at around 3 MHz ⋅ mm, would be suitable when testing for shallow defects; however, it is clear that both the SH0 and SH1 modes can exist at this frequency–thickness product. This can complicate the inspection process and, therefore, limit defect detectability. This article investigates the possibility of a single-mode excitation of the SH1 mode at around 3 MHz ⋅ mm. The ability of this method toward detecting very shallow defects (<10% cross-sectional thickness loss) has also been studied. By means of analytical predictions and finite element, it is shown that a signal dominated by the SH1 mode can be generated using a single permanent periodic magnet (PPM) electromagnetic acoustic transducer (EMAT) (PPM EMAT). All predictions are then backed up by experimental measurements. It is also shown that, by studying the reflection coefficient of the SH1 mode, the pure SH1 mode can be used to detect defects as shallow as 5% thickness loss from a 500-mm stand-off. These defects would otherwise be missed by standard, lower frequency guided wave testing.
Date Issued
2021-03
Date Acceptance
2020-07-16
Citation
IEEE Transactions on Ultrasonics, Ferroelectrics and Frequency Control, 2021, 68 (3), pp.818-828
ISSN
0885-3010
Publisher
Institute of Electrical and Electronics Engineers
Start Page
818
End Page
828
Journal / Book Title
IEEE Transactions on Ultrasonics, Ferroelectrics and Frequency Control
Volume
68
Issue
3
Copyright Statement
This work is licensed under a Creative Commons Attribution 4.0 License. For more information, see https://creativecommons.org/licenses/by/4.0/
License URL
Identifier
http://gateway.webofknowledge.com/gateway/Gateway.cgi?GWVersion=2&SrcApp=PARTNER_APP&SrcAuth=LinksAMR&KeyUT=WOS:000623420600041&DestLinkType=FullRecord&DestApp=ALL_WOS&UsrCustomerID=1ba7043ffcc86c417c072aa74d649202
Subjects
2-D fast Fourier transform (FFT)
Acoustics
Bandwidth
defect sensitivity
Dispersion
Engineering
Engineering, Electrical & Electronic
Force
Inspection
mode-selectivity
permanent periodic magnet (PPM) electromagnetic acoustic transducers (EMAT)
Science & Technology
Sensitivity
shear-horizontal (SH) guided wave
Surface waves
Technology
Publication Status
Published
Date Publish Online
2020-07-22