The effect of stiffener parameters on the farfield sound radiation from composite beams: Experiment and theory

dc.contributor.advisor J. Adin Mann, III
dc.contributor.advisor Daniel O. Adams
dc.contributor.author Slaughter, Julie
dc.contributor.department Aerospace Engineering
dc.date 2018-08-23T14:52:06.000
dc.date.accessioned 2020-06-30T07:19:27Z
dc.date.available 2020-06-30T07:19:27Z
dc.date.copyright Wed Jan 01 00:00:00 UTC 1997
dc.date.issued 1997
dc.description.abstract <p>The effects of spatial and material variations on farfield sound radiation from carbon/epoxy composite beams were investigated. Specifically, the geometry of a single stiffener of carbon/epoxy embedded in a beam, periodically spaced stiffeners along the length of a beam, and single stiffeners of different materials embedded in beams were all investigated. Because of a lack of methods to sufficiently model the details of spatially varying material properties, experimental data were used to identify important parameters that needed to be included in a model. Vibration testing was performed for three frequency ranges: 500 Hz to 1500 Hz, 1500 Hz to 2500 Hz, and 2500 Hz to 3500 Hz. The geometry of a single stiffener of carbon/epoxy affected the region of the stiffener that radiated sound. Periodically spaced stiffeners tended to have a global stiffening effect at lower frequencies and to act like individual stiffeners for frequencies where the wavelength is shorter than the stiffener. A stiffener of viscoelastic material reduced the sound power radiated from the region of the stiffener, and stiffeners of other materials radiated sound from the ends of the stiffener. Vibration experiments were performed on fiber-reinforced composite beams to verify a cubic spline based solution of a simple Euler-Bernoulli beam model. The model seemed to accurately predict the shape and location of farfield sound radiation from stiffeners. However, limitations on the available boundary conditions prevented accurate prediction of the magnitude of sound radiation. The model was then used to predict sound radiation from beams with varying stiffener bond lengths and these results were experimentally verified. In general a longer stiffener bond length causes less sound radiation. However, there seems to be a critical length at which the sound radiation reaches a maximum.</p>
dc.format.mimetype application/pdf
dc.identifier archive/lib.dr.iastate.edu/rtd/12246/
dc.identifier.articleid 13245
dc.identifier.contextkey 6767192
dc.identifier.doi https://doi.org/10.31274/rtd-180813-13520
dc.identifier.s3bucket isulib-bepress-aws-west
dc.identifier.submissionpath rtd/12246
dc.identifier.uri https://dr.lib.iastate.edu/handle/20.500.12876/65593
dc.language.iso en
dc.source.bitstream archive/lib.dr.iastate.edu/rtd/12246/r_9737759.pdf|||Fri Jan 14 19:16:34 UTC 2022
dc.subject.disciplines Applied Mechanics
dc.subject.disciplines Materials Science and Engineering
dc.subject.disciplines Mechanical Engineering
dc.subject.keywords Aerospace engineering and engineering mechanics
dc.subject.keywords Engineering mechanics
dc.title The effect of stiffener parameters on the farfield sound radiation from composite beams: Experiment and theory
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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