Abstract
The vibration suppression becomes very important for designing the helicopter to ensure the comfort and safety. In some kind of helicopters, the pendulum absorbers are adopted for the purposes to reduce the vibrations. But, the drawback is that the dimensions of the pendulum absorbers are determined by the anti-resonance concept based on the linear theory. Also, its characteristics are not analyzed completely. 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. In our previous report, we proposed a 2-degree-of-freedom model of the rotor blade and the pendulum absorber. The blade is considered as a rigid body. The blade is excited by giving a sinusoidal deflection at its end. In this paper, we proposed a 3-degree-of-freedom model by adding the fuselage, and gave periodic forces on the blade. The vibration is analyzed considering nonlinear characteristics. We show that the vibration is well-suppressed by the pendulum absorbers.
