A dominant source of noise in a helicopter cabin is the meshing of the gears in the main rotor gearbox. The main structural noise transmission path from this gearbox to the cabin is through the gearbox support struts, and this is the transmission path which is the subject of this paper. An experimental study is described which quantifies the way in which vibration propagates through one of these struts and the experimental results are interpreted with the aid of some simple analytical models. The contribution of the various modes of vibration to the transmission of the structure-borne noise is quantified by calculating the kinetic energy of the receiving structure from measured data. The results show that although the dominant mode of vibration is longitudinal, flexural resonances occur at some frequencies, and the contribution of the flexural vibration to the kinetic energy of the receiving structure at these frequencies can be comparable with that due to the longitudinal motion. It is demonstrated that the lateral behavior of the strut is dependent upon the static loading but the longitudinal behavior is relatively insensitive to this loading.
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July 1998
Research Papers
Noise Propagation Through Helicopter Gearbox Support Struts—An Experimental Study
M. J. Brennan,
M. J. Brennan
ISVR, University of Southampton, Southampton, Hampshire, UK
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S. J. Elliott,
S. J. Elliott
ISVR, University of Southampton, Southampton, Hampshire, UK
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K. H. Heron
K. H. Heron
Air Systems Sector, Defence Research Agency, Farnborough, Hampshire, UK
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M. J. Brennan
ISVR, University of Southampton, Southampton, Hampshire, UK
S. J. Elliott
ISVR, University of Southampton, Southampton, Hampshire, UK
K. H. Heron
Air Systems Sector, Defence Research Agency, Farnborough, Hampshire, UK
J. Vib. Acoust. Jul 1998, 120(3): 695-704 (10 pages)
Published Online: July 1, 1998
Article history
Received:
June 1, 1995
Revised:
March 1, 1997
Online:
February 26, 2008
Citation
Brennan, M. J., Elliott, S. J., and Heron, K. H. (July 1, 1998). "Noise Propagation Through Helicopter Gearbox Support Struts—An Experimental Study." ASME. J. Vib. Acoust. July 1998; 120(3): 695–704. https://doi.org/10.1115/1.2893886
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