Development of a spherically focused capacitive-film air-coupled ultrasonic transducer and a leak location array sensor for long-endurance spacecraft

dc.contributor.advisor Dale E. Chimenti
dc.contributor.advisor Ron Roberts
dc.contributor.author Song, Jun-Ho
dc.contributor.department Aerospace Engineering
dc.date 2018-08-24T18:00:56.000
dc.date.accessioned 2020-06-30T08:03:58Z
dc.date.available 2020-06-30T08:03:58Z
dc.date.copyright Sat Jan 01 00:00:00 UTC 2005
dc.date.issued 2005-01-01
dc.description.abstract <p>This research work is focused on the development of a spherically focused (no-mirror) capacitive-film air-coupled ultrasonic transducer and a leak location array sensor for long-endurance spacecraft. For the development of a spherically focused capacitive-film air-coupled ultrasonic transducer, two transducers have been designed, fabricated, and their performance characterized, using a spherically deformed backplate and film. One has a 10-mm diameter and 25.4-mm geometric focal length, and another has a 50-mm diameter and 50.8-mm geometric focal length. Both spherically focused transducers have frequency spectra centered at 805 kHz with -6-dB points at 400 kHz and 1200 kHz. By performing rigorous feasibility tests; a flexible copper/polyimide circuit board material is employed as a backplate in place of the conventional silicon substrate. Utilizing its deformability and ease of microfabrication, we have demonstrated that spherically focused air-coupled ultrasonic transducers can be made to function without the need of an external focusing device, such as a zone plate or an acoustic mirror. We have also invented a simple and easily applied method to conform the metalized polymer film onto a spherically curved backplate, while suppressing wrinkling on the film. Good agreement has been shown between measurement and theory, suggesting that our transducers behave as ideal spherically focused piston transducers;For the development of a leak location array sensor for long-endurance spacecraft, we have developed and experimentally demonstrated a sensitive and reliable means to locate an air leak in a plate-like structure. The goals of this work are accomplished by developing a sophisticated leak location algorithm and a two-dimensional PZT array sensor. The proposed leak location algorithm is highly effective in finding the direction of the leaks, using a minimal number of sensors, and needing less computation time while still achieving high accuracy. In addition, it accounts for the multi-mode dispersive characteristics in a plate-like structure, and utilizes structure-borne noise generated by turbulence at an air leak. This leak location algorithm is implemented by a prototype of a 64-element array sensor.</p>
dc.format.mimetype application/pdf
dc.identifier archive/lib.dr.iastate.edu/rtd/1794/
dc.identifier.articleid 2793
dc.identifier.contextkey 6105431
dc.identifier.doi https://doi.org/10.31274/rtd-180813-15416
dc.identifier.s3bucket isulib-bepress-aws-west
dc.identifier.submissionpath rtd/1794
dc.identifier.uri https://dr.lib.iastate.edu/handle/20.500.12876/71808
dc.language.iso en
dc.source.bitstream archive/lib.dr.iastate.edu/rtd/1794/r_3200481.pdf|||Fri Jan 14 21:31:25 UTC 2022
dc.subject.disciplines Aerospace Engineering
dc.subject.disciplines Electrical and Computer Engineering
dc.subject.keywords Aerospace engineering
dc.subject.keywords Engineering mechanics
dc.title Development of a spherically focused capacitive-film air-coupled ultrasonic transducer and a leak location array sensor for long-endurance spacecraft
dc.type article
dc.type.genre dissertation
dspace.entity.type Publication
relation.isOrgUnitOfPublication 047b23ca-7bd7-4194-b084-c4181d33d95d
thesis.degree.level dissertation
thesis.degree.name Doctor of Philosophy
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