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Active Damping Using Distributed Anisotropic ActuatorsA 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.
Document ID
20100039496
Acquisition Source
Langley Research Center
Document Type
Conference Paper
Authors
Schiller, Noah H.
(NASA Langley Research Center Hampton, VA, United States)
Cabell, Randolph H.
(NASA Langley Research Center Hampton, VA, United States)
Quinones, Juan D.
(Puerto Rico Univ. Mayaguez, Puerto Rico)
Wier, Nathan C.
(Michigan Technological Univ. Houghton, MI, United States)
Date Acquired
August 25, 2013
Publication Date
November 12, 2010
Subject Category
Mechanical Engineering
Report/Patent Number
NF1676L-10292
IMCEC2010-37503
Meeting Information
Meeting: ASME 2010 International Mechanical Engineering Congress and Exposition (IMECE2010)
Location: Vancouver
Country: Canada
Start Date: November 12, 2010
End Date: November 18, 2010
Sponsors: American Society of Mechanical Engineers
Funding Number(s)
WBS: WBS 877868.02.07.07.04.01
Distribution Limits
Public
Copyright
Public Use Permitted.
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