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Active Damping Using Distributed Anisotropic Actuators

[+] Author Affiliations
Noah H. Schiller, Randolph H. Cabell

NASA Langley Research Center, Hampton, VA

Juan D. Quinones

University of Puerto Rico, Mayaguez, Puerto Rico

Nathan C. Wier

Michigan Technological University, Houghton, MI

Paper No. IMECE2010-37503, pp. 73-80; 8 pages
doi:10.1115/IMECE2010-37503
From:
  • ASME 2010 International Mechanical Engineering Congress and Exposition
  • Volume 13: Sound, Vibration and Design
  • Vancouver, British Columbia, Canada, November 12–18, 2010
  • Conference Sponsors: ASME
  • ISBN: 978-0-7918-4450-2
  • Copyright © 2010 by ASME

abstract

A helicopter structure experiences substantial high-frequency mechanical excitation from powertrain components such as gearboxes and drive shafts. The resulting structure-borne vibration excites the windows which then radiate sound into the passenger cabin. In many cases the radiated sound power can be reduced by adding damping. This can be accomplished using passive or active approaches. Passive treatments such as constrained layer damping tend to reduce window transparency. Therefore this paper focuses on an active approach utilizing compact decentralized control units distributed around the perimeter of the window. Each control unit consists of a triangularly shaped piezoelectric actuator, a miniature accelerometer, and analog electronics. Earlier work has shown that this type of system can increase damping up to approximately 1 kHz. However at higher frequencies the mismatch between the distributed actuator and the point sensor caused control spillover. This paper describes new anisotropic actuators that can be used to improve the bandwidth of the control system. The anisotropic actuators are composed of piezoelectric material sandwiched between interdigitated electrodes, which enables the application of the electric field in a preferred in-plane direction. When shaped correctly the anisotropic actuators outperform traditional isotropic actuators by reducing the mismatch between the distributed actuator and point sensor at high frequencies. Testing performed on a Plexiglas panel, representative of a helicopter window, shows that the control units can increase damping at low frequencies. However high frequency performance was still limited due to the flexible boundary conditions present on the test structure.

Copyright © 2010 by ASME

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