Investigation Of Helicopter Main Reducer Dynamic Anti-Resonance Vibration Isolation Platform

Helicopter vibration is mainly caused by the rotor and affected the fuselage through the main reducer,which can bring negative impact on the operation of the helicopter.Thus,it is essential to reduce the vibration level of the helicopter in the design and development process of the helicopter.Installing the isolation system between the main reducer and the fuselage is the mainstream way of helicopter vibration isolation.This paper analyzes three types of dynamic anti-resonance vibration isolator(DAVI)in detail and kinematics equations are established.According to the characteristics and applicable range of different vibration isolators,the fluid elastomer vibration isolator is mainly discussed.Then,three types of multi-layer vibration isolation system based on fluid elastomer vibration isolator are put forward and analyzed.The main contents and results are as follows:1.Dynamic anti-resonance principle analysisThe mathematical model of the dynamic anti-resonance isolator is established,the kinematics equation is derived and the dynamic simulation is carried out to find the relationship between the displacement transmissibility and the amplification ratio and etc.The focal vibration isolation system linked with mechanical dynamic anti resonance vibration isolator is analyzed.2.Performance analysis and design of hydraulic and fluid elastomer isolatorDiscussion is focused on hydraulic and fluid elastomer vibration isolator.A detailed analysis of the bandwidth and cut-off frequency of the hydraulic isolator is conducted.A mathematical model of the multilayer hydraulicisolator is established,and optimized design for the 2 degree-of-freedom system for larger bandwidth and lower cutoff frequency is discussed.Then,the evaluation method of bellows stiffness is given.Fluid elastomer isolator and hydraulic vibration isolator has the same performance in theory and its damping model is given.Calculation method of stiffness of the rubber is summarized.Structure design and vibration experiment is conducted consequently.The experimental result shows that the isolator has excellent isolation efficiency of the isolator at a single frequency.3.Multi degree-of-freedom vibration isolation system designBased on the fluid elastomer isolator,3 kinds of vibration isolation system with multi degree-of-freedom are proposed.Adams and ANSYS dynamics modeling is built and simulation is conducted.The results show that the multi degree-of-freedom vibration isolation system has good vibration isolation effect with exaction from several directions,and the vibration isolation frequency is consistent with which of the single degree-of-freedom isolator.The prototype design of multi degree-of-freedom vibration isolation system is carried out according to the vibration isolation requirements.