Research On Bifilar Pendulum Absorber

As the main vibration source of a helicopter, the rotor brings so many dynamic problems. How toreduce the impact of the rotor to the vibration of a helicopter has became a focused dynamic subjectof helicopters. Mounted on the main rotor hub of rotorcraft, the bifilar pendulum vibration absorbercan absorb in-plane rotor vibrations at a specified frequency effectively. As it is very useful to reducethe vibration levels, the bifilar pendulum vibration absorber is widely used in modern helicopters.This paper establishes the mathematical model of an asymmetric bifilar pendulum vibrationabsorber with four support arms by using multi-body dynamics. The asymmetry of the absorberstructure and acceleration impedance of the fuselage is considered in the model. The fourth orderRunge-Kutta algorithm is used in time integration of the nonlinear dynamic formulations deducedfrom the model, so that the efficiency of vibration absorption could be calculated. And the calculationresult of the absorber is matched with the test result of UH-60. After calculation and analysis ofdifferent combinations which have different lengths of support arms or weight of turning mass indifferent excitation, by comparing with the dynamic characteristics of bifilar pendulum absorber in asymmetric structure, the asymmetric bifilar pendulum absorber with a proper choice of structuralparameters plays a better role in the large excitation. It can get a high and stable absorption efficiencyin a wide range of excitation. After that, the model is established in ADAMS. The result fromADAMS is also matched with the calculation result. As it takes too much time for simulation,ADAMS can be used for further design of bifilar absorber instead of preliminary design orconfiguration choice. At last, the experiment of the dynamic characteristics of bifilar pendulumvibration absorber is designed in this paper to lay the foundation for the dynamic characteristicsresearch of bifilar absorber by experiment in the future.