This thesis presents a new active-passive treatment developed to reduce structural vibrations and their associated radiated sound. It is a contribution to the research of efficient and low cost devices that implement the advantages of active and passive noise control techniques. A theoretical model has been developed to investigate the potential of this new "active-passive distributed absorber". The model integrates new functions that make it extremely stable numerically. Using this model, a genetic algorithm has been used to optimize the shape of the active-passive distributed absorber. Prototypes have been designed and their potential investigated. The device subsequently developed can be described as a skin that can be mechanically and electrically tuned to reduce unwanted vibration and/or sound. It is constructed from the piezoelectric material polyvinylidene fluoride (PVDF) and thin layers of lead. The tested device is designed to weight less than 10% of the main structure and has a resonance frequency around 1000 Hz. Experiments have been conducted on a simply supported steal beam (24"x2"x1/4"). Preliminary results show that the new treatment out-performs active-passive point absorbers and conventional constrained layer damping material. The compact design and its efficiency make it suitable for many applications especially in the transportation industry. This new type of distributed absorber is totally original and represent a potential breakthrough in the field of acoustics and vibration control. / Master of Science
| Identifer | oai:union.ndltd.org:VTETD/oai:vtechworks.lib.vt.edu:10919/10105 |
| Date | 13 November 1998 |
| Creators | Cambou, Pierre E. |
| Contributors | Mechanical Engineering, Fuller, Christopher R. |
| Publisher | Virginia Tech |
| Source Sets | Virginia Tech Theses and Dissertation |
| Detected Language | English |
| Type | Thesis |
| Format | ETD, application/pdf, application/pdf, application/pdf, application/pdf, application/pdf, application/pdf, application/pdf, application/pdf, application/pdf, application/pdf, application/pdf, application/pdf, application/pdf |
| Rights | In Copyright, http://rightsstatements.org/vocab/InC/1.0/ |
| Relation | Chapter_4.pdf, Chapter_3.pdf, Chapter_2.pdf, Chapter_1.pdf, appendix_e.pdf, appendix_d.pdf, appendix_c.pdf, appendix_b.pdf, thesis1.pdf, ref.pdf, intro.pdf, conclusion.pdf, appendix_a.pdf, vita.pdf |
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