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Proceedings Paper

Chamber-core structures for fairing acoustic mitigation
Author(s): Emil Ardelean; Andrew Williams; Nicholas Korshin; Kyle Henderson; Steven Lane; Robert Richard
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Paper Abstract

Extreme noise and vibration levels at lift-off and during ascent can damage sensitive payload components. Recently, the Air Force Research Laboratory, Space Vehicles Directorate has investigated a composite structure fabrication approach, called chamber-core, for building payload fairings. Chamber-core offers a strong, lightweight structure with inherent noise attenuation characteristics. It uses one-inch square axial tubes that are sandwiched between inner and outer face-sheets to form a cylindrical fairing structure. These hollow tubes can be used as acoustic dampers to attenuate the amplitude response of low frequency acoustic resonances within the fairing’s volume. A cylindrical, graphite-epoxy chamber-core structure was built to study noise transmission characteristics and to quantify the achievable performance improvement. The cylinder was tested in a semi-reverberant acoustics laboratory using bandlimited random noise at sound pressure levels up to 110 dB. The performance was measured using external and internal microphones. The noise reduction was computed as the ratio of the spatially averaged external response to the spatially averaged interior response. The noise reduction provided by the chamber-core cylinder was measured over three bandwidths, 20 Hz to 500 Hz, 20 Hz to 2000 Hz, and 20 Hz to 5000 Hz. For the bare cylinder with no acoustic resonators, the structure provided approximately 13 dB of attenuation over the 20 Hz to 500 Hz bandwidth. With the axial tubes acting as acoustic resonators at various frequencies over the bandwidth, the noise reduction provided by the cylinder increased to 18.2 dB, an overall increase of 4.8 dB over the bandwidth. Narrow-band reductions greater than 10 dB were observed at specific low frequency acoustic resonances. This was accomplished with virtually no added mass to the composite cylinder.

Paper Details

Date Published: 16 May 2005
PDF: 9 pages
Proc. SPIE 5760, Smart Structures and Materials 2005: Damping and Isolation, (16 May 2005); doi: 10.1117/12.600125
Show Author Affiliations
Emil Ardelean, Science Applications International Corp. (United States)
Andrew Williams, Air Force Research Lab. (United States)
Nicholas Korshin, U.S. Air Force Academy (United States)
Kyle Henderson, Air Force Research Lab. (United States)
Steven Lane, Air Force Research Lab. (United States)
Robert Richard, Boeing-SVS, Inc. (United States)

Published in SPIE Proceedings Vol. 5760:
Smart Structures and Materials 2005: Damping and Isolation
Kon-Well Wang, Editor(s)

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