Transmission of Gear Noise to Aircraft Interiors Prediction Methods,
KAMAN AEROSPACE CORP BLOOMFIELD CT
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Prediction of interior noise of helicopters due to drive train vibration ideally requires an analytical model of the entire dynamic system including airframe, transmission, and all attachments. This paper addresses the need for such a model and certain of the critical issues involved the inadequacy of finite element modeling in the acoustic frequency range the costs associated with assessment of parametric variations and the difficulty of incorporating new technology into existing computer programs. Potential solutions to these problems include use of combined test and analysis system identification to obtain better models component synthesis using frequency domain reduced models and a computer program known as DYSCO. This program has a general capability to modify and couple components in the time or frequency domain and can act as a repository for the latest analytical developments.