Design, Modeling And Testing Of A 6DOF Vibration Isolate System Used Magnetorheological Dampers

The vibration and noise level of helicopter is a core indicator of helicopter’s performance,which affects helicopter’s combat capability,such as shooting accuracy of weapons,comfort of occupants and stealth.Rotor is a main vibration sources of helicopter,whose vibration transfers to fuselage through transmission system composed of main reducer,etc.The vibration can be reduced effectively by vibration isolate equipment between main reducer and fuselage.However,the traditional vibration isolation equipment cannot meet the requirements of high vibration bandwidth and multi-direction vibration of the rotor-main reducer system.Therefore,a six-degrees-of-freedom vibration isolation system used magnetorheological fluid dampers(MRDs)is designed to research the feasibility of vibration of rotor and main system reducing,which is based on Stewart mechanism.The research contents are as follows(1)The dynamic model of the vibration isolation platform is established,and the structural parameters of the six-degree-of-freedom vibration isolation platform based on magnetorheological fluid damper are obtained by using this model combined with geometric analysis.(2)An efficient magnetorheological fluid damper is designed.Firstly,the working mode of the MRD is determined,and the function of the maximum damping force of the MRD is derived.Secondly,the magnetic circuit is designed according to electromagnetic theory and finite element simulation.Thirdly structural parameters and materials are determined by strength analysis.Finally,the Bingham model is used to simulate and verify the designed MRD.The final parameters of MRD are obtained and the three-dimensional model and engineering drawings are drawn.(3)The parameters of Bouc-Wen model of MRD are identified.According to the structural parameters of the designed MRD,the MRD devices are fabricated.The mechanical properties of the magnetorheological dampers are tested by W+B mechanical testing machine,and parameters of Bouc-Wen model are obtained by parameter identification method.(4)The simulation model of the vibration system is established and its vibration reduction performance is simulated and analyzed.According to the established dynamic model of vibration platform and the Bouc-Wen model of the MR damper,the simulation model of the vibration isolation platform is established in SimMechanics.The on-off control strategy for the vibration isolation platform is designed,which is verified by numerical simulation.(5)Vibration control performance of the vibration isolation platform is tested.The vibration control test system of the vibration isolation platform is established,which used three-axis vibration table to simulate the vibration of the rotor.The test system can realize the vibration control performance test of the vibration isolation system.The test results show that the vibration isolation system can effectively suppress the vibration amplification in the resonance region,and also has good vibration isolation effect in the high frequency region,which meets the needs of the helicopter to reduce the vibration isolation bandwidth.