Coupled rotor-flexible fuselage vibration reduction using open loop higher harmonic controlA fundamental study of vibration prediction and vibration reduction in helicopters using active controls was performed. The nonlinear equations of motion for a coupled rotor/flexible fuselage system have been derived using computer algebra on a special purpose symbolic computer facility. The trim state and vibratory response of the helicopter are obtained in a single pass by applying the harmonic balance technique and simultaneously satisfying the trim and the vibratory response of the helicopter for all rotor and fuselage degrees of freedom. The influence of the fuselage flexibility on the vibratory response is studied. It is shown that the conventional single frequency higher harmonic control is capable of reducing either the hub loads or only the fuselage vibrations but not both simultaneously. It is demonstrated that for simultaneous reduction of hub shears and fuselae vibrations a new scheme called multiple higher harmonic control is required.
Document ID
19910047408
Acquisition Source
Legacy CDMS
Document Type
Conference Paper
Authors
Papavassiliou, I. (California Univ. Los Angeles, CA, United States)
Friedmann, P. P. (California Univ. Los Angeles, CA, United States)
Venkatesan, C. (California, University Los Angeles, United States)
Date Acquired
August 14, 2013
Publication Date
January 1, 1991
Subject Category
Aircraft Stability And Control
Report/Patent Number
AIAA PAPER 91-1217
Meeting Information
Meeting: AIAA/ASME/ASCE/AHS/ASC Structures, Structural Dynamics, and Materials Conference