Title page for ETD etd-08182009-143024


Type of Document Master's Thesis
Author Harne, Ryan
Author's Email Address rharne@vt.edu
URN etd-08182009-143024
Title Novel Lightweight Noise and Vibration Control Treatments for Marine Structures
Degree Master of Science
Department Mechanical Engineering
Advisory Committee
Advisor Name Title
Fuller, Christopher R. Committee Chair
Johnson, Martin E. Committee Member
Papenfuss, Cory M. Committee Member
Keywords
  • marine structures
  • passive vibration control
  • broadband noise control
  • HG blankets
  • distributed vibration absorbers
Date of Defense 2009-08-10
Availability unrestricted
Abstract
This thesis presents the development and testing of distributed vibration absorber designs with specific application to heavy plates for the reduction of vibration and sound radiation. Two particular designs, already under investigation for use on thin panels or composite materials, were adapted to passively reduce broadband vibration and noise from large and heavy plates. These absorbers are referred to as Distributed Vibration Absorbers [DVAs] and Heterogeneous [HG] Blankets. Numerical models were developed, based on the theory of sound propagation through layered media and the vibration of plates, to simulate the performance of such absorbers for a variety of applications and media characteristics. The new absorber designs were then tested on a large, marine-type plate (4 feet by 2 feet by 1/4 inch) and showed both broadband noise and vibration control from 60 Hz to 5 kHz. DVAs could reduce the vibrating plate resonance magnitudes on the order of 15 dB at their tuning frequencies while providing overall vibration reduction of 5 dB or greater at higher frequencies. HG blankets were also capable of reducing plate resonance vibration up to 15 dB at their tuning frequencies and produced overall vibration reduction of 5 dB at higher frequencies. These absorbers are entirely passive, i.e. requiring no controller or prior modal testing of the structure, were placed randomly during testing, and are designed to contribute less than 10% additional mass to the structure, making them a robust vibration and noise control solution.
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