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The role of rotor impedance in the vibration analysis of rotorcraftIn an improved method which retains the advantage of separate treatment of rotor and airframe, the rotor impedance is used to correct the input to the airframe. This improved method is illustrated for a strongly idealized case of vertical excitation and then for rolling and pitching moment excitation of a four bladed hingeless rotor on an up-focussing flexible mount. Contrary to the usual approach that represents aeroelastic blade motions by a series of normal blade modes in vacuum, the aeroelastic rotor impedances are computed directly with a finite blade element method that includes aerodynamics. The rotor impedance matrix for three or more blades is determined from the root moment impedance for a single blade by a simple multiblade transformation rule. Force and moment amplitudes transferred from the rotor to the support are found to be critically dependent on the support dynamics.
Document ID
19790034640
Acquisition Source
Legacy CDMS
Document Type
Conference Proceedings
Authors
Hohenemser, K. H.
(Washington University St. Louis, Mo., United States)
Yin, S.-K.
(Bell Helicopter Textron Fort Worth, Tex., United States)
Date Acquired
August 9, 2013
Publication Date
January 1, 1978
Subject Category
Structural Mechanics
Meeting Information
Meeting: European Rotorcraft and Powered Lift Aircraft Forum
Location: Stresa
Country: Italy
Start Date: September 13, 1978
End Date: September 15, 1978
Accession Number
79A18653
Funding Number(s)
CONTRACT_GRANT: NAS2-7613
Distribution Limits
Public
Copyright
Other

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