Development Of A Fluid-elastomer Vibration Isolator For Semi-active Helicopter Pylon Isolation

The hub force of the rotor is the chief part of the helicopter airframe vibration source. The hub force transmit from the rotor to the fuselage via the rotor shaft, the main gear-box and the connection devices between the main gear-box and the helicopter airframe and make the airframe produces strong vibration. Therefore, it will be an efficient method to select an appropriate vibration isolation device as the connection device between the helicopter main gearbox and the fuselage. Fluid elastomer isolator is a kind of high-efficient vibration isolation equipment with simple structure, light weight and less space occupation. In recent years, Fluid elastomer isolator is increasingly used in helicopter pylon vibration isolation in foreign countries. However, with the continuous improvement of the requirement for helicopter vibration level, the traditional passive vibration isolation device is more and more difficult to complete the vibration control target. The semi-active vibration control methods, whose vibration isolation effect is better and adaptability is stronger, has became the research hotspot.In this paper a kind of new type fluid elastomer isolator which can be used in the semi-active vibration isolation of the helicopter main gearbox has been designed. The dynamic model of the fluid elastomer isolator is established, and its dynamic equation is deduced, and the vibration isolation frequency formula is derived. This paper also discuss the parameters that can influence the vibration isolation frequency of fluid elastomer isolator. On this basis, chooses the stiffness of the isolator and a variable stiffness spring is designed. A three loops voice coil motor is selected as the actuator to separate the leaf springs to change the stiffness to achieve the aim that the isolation frequency of the fluid elastomer isolator can fit the change of the frequency of vibration. With the development of the variable stiffness spring, a new type of variable stiffness fluid elastomer isolator is designed. By using the software MSC. Adams, the simulative frequency response results is carried out and the simulation results and the calculation results agree well that can prove that the variable stiffness fluid elastomer isolator can the task of the isolator in semi-active vibration isolation. And the assemble model is finally established with CATIA.