Accession Number : ADA119467

Title :   Helicopter Vibration Suppression Using Simple Pendulum Absorbers on the Rotor Blade.

Descriptive Note : Final rept.,


Personal Author(s) : Pierce,G Alvin ; Hamouda,M-Nabil H

PDF Url : ADA119467

Report Date : Sep 1982

Pagination or Media Count : 140

Abstract : The objectives of the present investigation are: (1) Develop a mathematical model to represent the blade-pendulum system. A single nonuniform rotor blade with a hingeless hub restraint undergoing coupled flapwise bending, chordwise bending, and torsional vibrations is considered. Simple pendulum absorbers are individually treated for both flap and lead-lag types of motion. The blade is excited by an azimuthal harmonic variation of spanwise airload distributions associated with the elastic deformations and the cyclic pitch environment of forward flight; (2) Find the dynamic response characteristics of the blade-pendulum system, using the transfer matrix method; (3) Determine the optimum pendulum tuning to suppress the hub reactions. This entails the minimization of these reactions by appropriate variations of the pendulum parameters for a given excitation frequency. The pendulum parameters include the uncoupled pendulum frequency, hinge spanwise location and pendulum mass; and (4) Conduct a parametric study of the optimum tuned configuration. The parameters to be varied include pendulum hinge offset, precone, prepitch and pretwist. The intention of this investigation is to document the effects of these parameters on the optimum configuration previously established and thereby provide useful design criteria for future installations of pendulum absorbers.

Descriptors :   *Vibration, *Rotor blades(Rotary wings), *Helicopters, *Absorbers(Equipment), *Mathematical models, Pendulums, Aerodynamic forces, Dynamic response, Hubs, Fuselages, Attenuators, Suppression, Distribution, Shock mitigation, Pitch(Motion), Hinges, Elastic properties

Subject Categories : Aerodynamics
      Numerical Mathematics

Distribution Statement : APPROVED FOR PUBLIC RELEASE