Research On Dynamic Characteristics And Semi-active Control Of The Variable Parameters Magnetorheological Dampers

Large high-speed machinery such as high-speed train,aircraft wing,aeroengine are important equipments in modern industrial society.When the relative speed of the mechanical moving load reaches a certain speed,the system has the potential to enter a state of instability and the vibration increases sharply,which seriously affects the safety of the organization operation.The semi-active control method is adopted to solve this problem instead of the traditional passive dampers.The MR dampers are typical semi-active control devices,which have been widely applied in the vibration isolation system of vehicles,aircrafts and constructions.Normally,MRF dampers are used as variable damping devices,because its stiffness can only produce small changes once the shock absorber is manufactured.Another MR material,MRE,whose modulus can be controlled by an applied magnetic field while with small stroke.Therefore,MR dampers with variable stiffness and damping properties are researched and are expected to have distinguished vibration reduction performance.In this dissertation,a compact variable stiffness MR damper is introduced,whose damping and stiffness characteristics can be controlled by changing the currents applied on the chambers respectively.To further illustrate the variable stiffness mechanism of the damper,the physical models for three working stages of the variable stiffness MR dampers are analyzed and built.The proposed physical model is verified through simulations and experiments.The influence factors which affect the equivalent stiffness and the variable stiffness capability are quantitatively analyzed to provide the design guidance for the practice.The control model of MRF dampers is composed of forward model and reverse model.Based on several basic parametric models,a forward model for MR damper is established to describe the relationship between the output damping force of MRF damper and the relative movement of the piston under different control currents.Combined with the MTS experimental results of the dual-output MR damper,the parameters of the model are identified.The input current that corresponds to the damping force is obtained using a reverse model derived by the current control function.Finally,the semi-active control algorithms for magnetorheological damper are studied in this dissertation.The control effects of several different control strategies are compared through simulation,including passive control,skyhook control and skyhook&ground sliding mode control strategy.