High contrast air-coupled acoustic imaging with zero group velocity Lamb modes

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dc.contributor.author Holland, Stephen
dc.contributor.author Holland, Stephen
dc.contributor.author Chimenti, Dale
dc.contributor.department Aerospace Engineering
dc.date 2018-02-13T03:15:42.000
dc.date.accessioned 2020-06-29T22:44:46Z
dc.date.available 2020-06-29T22:44:46Z
dc.date.copyright Wed Jan 01 00:00:00 UTC 2003
dc.date.embargo 2012-11-20
dc.date.issued 2003-07-01
dc.description.abstract <p>The well known zero in the group velocity of the first-order symmetric (S<sub>1</sub>) plate wave mode has been exploited in air-coupled ultrasonic imaging to obtain significantly higher sensitivity than can be achieved in conventional air-coupled scanning. At the zero group velocity point at the frequency minimum of the S<sub>1</sub>mode, a broad range of wavenumbers couple into the first-order symmetric mode at nearly a constant frequency, greatly enhancing transmission at that frequency. Coupled energy remains localized near the coupling point because the group velocity is zero. We excite the mode with a broadband, focussing, air-coupled transducer at the frequency of the zero group velocity point in the S<sub>1</sub> mode. By exploiting the efficient coupling at the zero group velocity frequency, we have easily imaged a single layer of Scotch tape attached to a 6.4-mm thick Plexiglas plate and 3.2-mm Teflon inserts in a composite laminate.</p>
dc.description.comments <p>This is a post-print of a proceeding from <em>Ultrasonics</em>, 42, no. 1–9 (April 2004): 957–960, doi: <a href="http://dx.doi.org/10.1016/j.ultras.2003.12.009" target="_blank">10.1016/j.ultras.2003.12.009</a>.</p>
dc.identifier archive/lib.dr.iastate.edu/aere_conf/1/
dc.identifier.articleid 1000
dc.identifier.contextkey 3481028
dc.identifier.s3bucket isulib-bepress-aws-west
dc.identifier.submissionpath aere_conf/1
dc.identifier.uri https://dr.lib.iastate.edu/handle/20.500.12876/1885
dc.language.iso en
dc.source.bitstream archive/lib.dr.iastate.edu/aere_conf/1/Holland_2004_HighContrastAirCoupled.pdf|||Fri Jan 14 17:27:57 UTC 2022
dc.subject.disciplines Aerospace Engineering
dc.subject.keywords nondestructive testing
dc.subject.keywords nondestructive evaluation
dc.subject.keywords Lamb waves
dc.subject.keywords Guided modes
dc.subject.keywords Zero group velocity
dc.subject.keywords Ultrasonic imaging
dc.subject.keywords Air-coupled ultrasound
dc.subject.keywords S1
dc.title High contrast air-coupled acoustic imaging with zero group velocity Lamb modes
dc.type article
dc.type.genre conference
dspace.entity.type Publication
relation.isAuthorOfPublication dea444ce-079d-483e-8db1-c33100203381
relation.isOrgUnitOfPublication 047b23ca-7bd7-4194-b084-c4181d33d95d
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