Abstract. To develop a coupled rotor/flexible fuselage model for vibration reduction studies, the equation of coupled rotor-fuselage is set up based on the theory of multi-body dynamics, and the dynamic analysis model is established with the software MSC.ADMAS and MSC.NASTRAN. The frequencies and vibration acceleration responses of the system are calculated with the model of coupled rotor-fuselage, and the results are compared with those of uncoupled modeling method. Analysis results showed that compared with uncoupled model, the dynamic characteristic obtained by the model of coupled rotor-fuselage are some different. The intrinsic frequency of rotor is increased with the increase of rotational velocities. The results also show that the flying speed has obvious influence on the vibration acceleration responses of the fuselage. The vibration acceleration response in the vertical direction is much higher at the low speed and high speed flight conditions.

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Using parameterized dynamic Bingham model to describe the relationship between active control actuator movement and damping force. SIMULINK emulation module of nonlinear actuator movement characteristics and compared with test data has been achieved by adopting MTLAB. According to the active system of displacement, velocity, acceleration and the desired damping force, the control current inverse model has been obtained based on fuzzy control theory. The validity and correctness of the simulation model are verified by the test results of variable current inverse. Fixed frequency excitation and real flying helicopters floor vibration data are adapted respectively to simulation, and the damping effect of the control system is obtained through simulation analysis.

In order to reduce the two main vibration frequency of the variable speed helicopter, an anti-resonance vibration isolator with double frequency vibration isolation is designed. First, the dynamic formula of the dual frequency vibration isolator was deduced based on the traditional dynamic anti-resonance theory. With the formula, the natural frequency, antiresonant frequency and transmissivity of the isolator are obtained. Then, the sensitivity of the performance and efficiency for the isolator is analyzed. The effects of design parameters such as secondary spring stiffness and secondary vibration isolation mass on the natural frequency and vibration isolation frequency of the isolator are obtained. The property test and vibration test are carried out. The calculation and test results show that the isolator has two vibration isolation frequency. The secondary vibration isolation efficiency is more than 60%, and the antiresonance frequency and efficiency of the isolator are both affected by the design parameters.