| At present,the traditional oil type shimmy damper is one of the most widely used and effective methods to suppress the nose wheel shimmy in the current aircraft.Under normal conditions,the occurrence of shimmy can be effectively suppressed,but in the course of aircraft using,aircraft load,runway crosswind,runway surface roughness and other factors,shimmy occurs from time to time.In order to get the best effect of shimmy control,it is necessary to study a new type of damp-controllable shimmy damper.The magnetorheological shimmy damper has the advantages of adjustable output damping force,wide range of adaptability,and it can realize semi-active control to different operating environments and operating conditions.The damping force produced by the magnetorheological shimmy damper mainly depends on the magnetorheological fluid flowing through the throttling channel of the shimmy damper.Therefore,to study the influence of the damper’s magnetorheological fluid flow state in output damping of the shimmy damper is one of the key issues to explore the damping mechanism.In this paper,the damping behavior of the magnetorheological shimmy damper are studied by the magnetorheological fluid behavior and the structure of the magnetorheological shimmy damper,and the flow field in the magnetorheological shimmy damper is theoretically analyzed and simulated.The correctness and effectiveness of the model are verified by experimental data.The main contents of this paper are as follows:1.By analyzing the components of magnetorheological fluid and the change process of magnetic particles in the magnetization process,the dynamic equation of magnetic particles was established and studied.According to the types of magnetorheological fluid involved,the appropriate magnetorheological fluid was selected and the corresponding constitutive model was established.2.Based on the structure of the magnetorheological shimmy damper involved,the influence factors of the output damping of magnetorheological shimmy damper were analyzed,and the dynamic model of magnetorheological shimmy damper was established by considering the influence of local losses.3.The flow field of the magnetorheological shimmy damper was simulated by ANSYS software,and the influence factors of the internal flow field of the magnetorheological shimmy damper on the output damping of the magnetorheological shimmy damper under different pore sizes were explored.The results show that the magnetorheological fluid flux and silting effect are the main factors that determine the initial damping and hysteresis effect of magnetorheological damper.4.Based on the Bingham constitutive model and kirchhoff’s law,the time delay model of the magnetorheological shimmy damper is established,and the main influencing factors of the magnetorheological shimmy damper’s response time are coil material,damping channel clearance,viscosity,etc. |
