Research On The Vibration Isolation Of Helicopter Gearbox Based On Dynamic Anti-resonance Technology

Rotor is the main vibration source of helicopter and the forces of rotor hub are transmitted to fuselage through main gearbox,which causes strong vibration to helicopter.Excessive vibration of helicopter would affect its ride comfort,reliability and duration,then how to reduce helicopter vibration level is an important issue to helicopter design.As an effective passive low-frequency vibration control method,dynamic anti-resonance technology has been widely studied in the field of helicopter gearbox vibration control.Based on the research of dynamic anti-resonance principle,this paper designs a new type of hydraulic dynamic anti-resonance isolator,and further tests the vibration isolation principle through experiments.In order to improve the effective vibration isolation frequency bandwidth of the vibration isolator,the vibration isolation bandwidth is analyzed and optimized.A single vibration isolator can only achieve vibration isolation in one direction,and an eight-struts dynamic anti-resonance vibration isolation platform is proposed in order to isolate rotor hub forces in all directions.The relationship between the vibration isolation platform and the vibration isolator legs is analyzed through dynamic modeling.The main contents are as follows:1)The dynamic anti-resonance isolator model is proposed considering rubber thickness,and an hydraulic dynamic anti-resonance isolator is designed and processed based on the experimental verification of the principle.The kinetic model is revised based on the experimental results,and further exploration of the relationship between the initial hydraulic pressure of the isolator and its isolation performance is conducted.2)In view of the shortcomings of dynamic anti-resonance vibration isolation bandwidth,two different forms of hydraulic dynamic antiresonance isolators are proposed.The vibration isolation bandwidth is analyzed and optimized.A tunable hydraulic dynamic vibration isolator is put forward and the relationship between the vibration isolation frequency and the structural parameters of the isolator is analyzed,and the parameters are optimized for larger vibration isolation bandwidth.3)To realize the vibration isolation of six degrees of freedom,a platform with eight dynamic anti-resonance vibration isolator struts is designed.The performance of the platform is analyzed through the kinematic and dynamic modeling.Analytical results indicate that the platform with eight dynamic anti-resonance vibration isolator struts can reduce the force transmission in all directions.