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EXPERIMENTAL STUDY OF ACOUSTICAL CHARACTERISTICS OF
HONEYCOMB SANDWICH STRUCTURES
by
Portia Renee Peters
A Dissertation Presented to the
FACULTY OF THE GRADUATE SCHOOL
UNIVERSITY OF SOUTHERN CALIFORNIA
In Partial Fulfillment of the
Requirements for the Degree
DOCTOR OF PHILOSOPHY
(MATERIALS SCIENCE)
May 2009
Copyright 2009 Portia Renee Peters
Object Description
| Title | Experimental study of acoustical characteristics of honeycomb sandwich structures |
| Author | Peters, Portia Renee |
| Author email | ppeters@usc.edu; portia.peters@gmail.com |
| Degree | Doctor of Philosophy |
| Document type | Dissertation |
| Degree program | Materials Science |
| School | Viterbi School of Engineering |
| Date defended/completed | 2009-03-23 |
| Date submitted | 2009 |
| Restricted until | Unrestricted |
| Date published | 2009-04-28 |
| Advisor (committee chair) | Nutt, Steven |
| Advisor (committee member) |
Kassner, Michael Flashner, Henryk |
| Abstract | Loss factor measurements were performed on sandwich panels to determine the effects of different skin and core materials on the acoustical properties. Results revealed inserting a viscoelastic material in the core's mid-plane resulted in the highest loss factor. Panels constructed with carbon-fiber skins exhibited larger loss factors than glass-fiber skins. Panels designed to achieve subsonic wave speed did not show a significant increase in loss factor above the coincidence frequency. The para-aramid core had a larger loss factor value than the meta-aramid core.; Acoustic absorption coefficients were measured for honeycomb sandwiches designed to incorporate multiple sound-absorbing devices, including Helmholtz resonators and porous absorbers. The structures consisted of conventional honeycomb cores filled with closed-cell polyurethane foams of various densities and covered with perforated composite facesheets. Honeycomb cores filled with higher density foam resulted in higher absorption coefficients over the frequency range of 50 - 1250 Hz. However, this trend was not observed at frequencies greater than 1250 Hz, where the honeycomb filled with the highest density foam yielded the lowest absorption coefficient among samples with foam-filled cores.; The energy-recycling semi-active vibration suppression method (ERSA) was employed to determine the relationship between vibration suppression and acoustic damping for a honeycomb sandwich panel. Results indicated the ERSA method simultaneously reduced the sound transmitted through the panel and the panel vibration. The largest reduction in sound transmitted through the panel was 14.3% when the vibrations of the panel were reduced by 7.3%.; The influence of different design parameters, such as core density, core material, and cell size on wave speeds of honeycomb sandwich structures was experimentally analyzed. Bending and shear wave speeds were measured and related to the transmission loss performance for various material configurations. The shear modulus of the core showed maximum influence on the wave speeds of the samples, while cell size did not have a significant influence on wave speeds or on transmission loss. Skin material affected wave speeds only in the pure bending regime. Honeycomb sandwich structures with a subsonic core and thus reduced wave speed showed increased transmission loss compared to samples without a subsonic core. |
| Keyword | acoustics; vibrations; honeycomb sandwich structures; composites |
| Language | English |
| Part of collection | University of Southern California dissertations and theses |
| Publisher (of the original version) | University of Southern California |
| Place of publication (of the original version) | Los Angeles, California |
| Publisher (of the digital version) | University of Southern California. Libraries |
| Provenance | Electronically uploaded by the author |
| Type | texts |
| Legacy record ID | usctheses-m2134 |
| Rights | Peters, Portia Renee |
| Repository name | Libraries, University of Southern California |
| Repository address | Los Angeles, California |
| Repository email | http://www.usc.edu/isd/libraries/services/ask_a_librarian/email/ |
| Filename | etd-Peters-2689 |
| Archival file | uscthesesreloadpub_Volume26/etd-Peters-2689.pdf |
Description
| Title | Page 1 |
| Full text | EXPERIMENTAL STUDY OF ACOUSTICAL CHARACTERISTICS OF HONEYCOMB SANDWICH STRUCTURES by Portia Renee Peters A Dissertation Presented to the FACULTY OF THE GRADUATE SCHOOL UNIVERSITY OF SOUTHERN CALIFORNIA In Partial Fulfillment of the Requirements for the Degree DOCTOR OF PHILOSOPHY (MATERIALS SCIENCE) May 2009 Copyright 2009 Portia Renee Peters |
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