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Damped Windows for Aircraft Interior Noise ControlWindows are a significant path for structure-borne and air-borne noise transmission into aircraft. To improve the acoustical performance, damped windows were fabricated using two or three layers of plexiglas with transparent viscoelastic damping material sandwiched between the layers. In this paper, numerical and experimental results are used to evaluate the acoustic benefits of damped windows. Tests were performed in the Structural Acoustic Loads and Transmission Facility at NASA Langley Research Center to measure the transmission loss for diffuse acoustic excitation and radiated sound power for point force excitation. Comparisons between uniform and damped plexiglas windows showed increased transmission loss of 6 dB at the first natural frequency, 6 dB at coincidence, and 4.5 dB over a 50 to 4k Hz range. Radiated sound power was reduced up to 7 dB at the lower natural frequencies and 3.7 dB over a 1000 Hz bandwidth. Numerical models are presented for the prediction of radiated sound power for point force excitation and transmission loss for diffuse acoustic excitation. Radiated sound power and transmission loss predictions are in good agreement with experimental data. A parametric study is presented that evaluates the optimum configuration of the damped plexiglas windows for reducing the radiated sound power.
Document ID
20040086707
Acquisition Source
Langley Research Center
Document Type
Preprint (Draft being sent to journal)
Authors
Buehrle, Ralph D. (NASA Langley Research Center Hampton, VA, United States)
Klos, Jacob (NASA Langley Research Center Hampton, VA, United States)
Gibbs, Gary P. (NASA Langley Research Center Hampton, VA, United States)
Date Acquired
September 7, 2013
Publication Date
January 1, 2004
Subject Category
Aircraft Design, Testing And Performance
Meeting Information
Meeting: Noise-Con 2004
Location: Baltimore, MD
Country: United States
Start Date: July 12, 2004
End Date: July 14, 2004
Funding Number(s)
OTHER: 23-781-10-13
Distribution Limits
Public
Copyright
Work of the US Gov. Public Use Permitted.

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