Vibration Suppression of a Helicopter Fuselage by Pendulum Absorbers : Rigid-Body Blades with Aerodynamic Excitation Force

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概要

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• Currently, some kinds of helicopters use pendulum absorbers in order to reduce vibrations. Present pendulum absorbers are designed based on the antiresonance concept used in the linear theory. However, since the vibration amplitudes of the pendulum are not small, it is considered that the nonlinearity has influence on the vibration characteristics. Therefore, the best suppression cannot be attained by using the linear theory. In a helicopter, periodic forces act on the blades due to the influences of the air thrust. These periodic forces act on the blades with the frequency which is the integer multiple of the rotational speed of the rotor. Our previous study proposed a 2-degree-of-freedom (2DOF) model composed of a rotor blade and a pendulum absorber. The blade was considered as a rigid body and it was excited by giving a sinusoidal deflection at its end. The present paper proposes a 3DOF model that is more similar to the real helicopter, since the freedom of the fuselage is added and the periodic forces are applied to the blade by aerodynamic force. The vibration is analyzed considering the nonlinear characteristics. The resonance curves of rotor blades with pendulum absorbers are obtained analytically and experimentally. It is clarified that the most efficient condition is obtained when the natural frequency of the pendulum is a little bit different from the frequency of the external force. Various unique nonlinear characteristics, such as bifurcations, are also shown.

著者

• Ishida Yukio

  Nagoya University

• NAGASAKA Imao

  Chubu Institute of Technology

• KOYAMA Takayuki

  Nagoya University

• FUJIMATSU Naoki

  Nagoya University

関連論文

• On the Internal Resonance in a Nonlinear Two-Degree-of-Freedom System : Forced Vibrations near the Higher Resonance Point When the Natural Frequencies Are in the Ratio 1:2
• Ultra-Subharmonic Oscillations in a Nonlinear Vibratory System
• Nonstationary vibrations of a rotating shaft with nonlinear spring characteristics during acceleration through critical speeds.
• On the Internal Resonance in a Nonlinear Two-degree-of-freedom System : When the Natural Frequencies Are in the Ratio 2 : 3
• Foreword
• Vibration Suppression of a Helicopter Using Pendulum Absorbers : First Elastic Mode of a Blade
• Vibration Suppression of a Helicopter Fuselage by Pendulum Absorbers : Rigid-Body Blades with Aerodynamic Excitation Force
• Preface

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