Study On Vibration Isolation Performance And Semi-active Control Of Quasi-zero Stiffness Magnetorheological Damping Floating Slab Track System

Because of the continuous development of urban rail transit in our country,the problem of environmental vibration and noise induced by urban rail transit is becoming more and more serious,and the orbit around the building,precision instruments will have a serious impact.At present,steel spring isolator is the most commonly used shock absorber in rail transit,but as a linear system,steel spring isolator can not take into account the low initial frequency and high load-carrying capacity,low-frequency vibration isolation performance is poor.Therefore,based on the principle of positive and negative stiffness parallel and magnetorheological damper semi-active vibration control,a quasi-zero stiffness magnetorheological damping floating slab track system is designed,the vibration isolation performance and semi-active control of the system are studied by means of theoretical analysis and simulation.It includes:magnetorheological damper mechanical performance analysis,system mechanical modeling,static analysis,dynamic analysis,vibration isolation performance analysis,semi-active control simulation analysis.The main research contents are as follows:(1)Mechanical performance analysis of magnetorheological damper.Firstly,the force-displacement and force-velocity relationships of the damper are obtained through mechanical performance tests.Then,Bingham model is selected to simulate the output damping force of magnetorheological damper,and the experimental data are used to identify the parameters of Bingham model.It is found that the Cullen damping force is related to the viscous damping and the current.Finally,based on Simulink simulation platform,the Bingham model of magnetorheological damper is established.The simulation results show that the Bingham model after parameter identification has good accuracy.(2)Static analysis of magnetorheological damper floating slab track system with quasi-zero stiffness.Firstly,the system mechanics model is established.Then,the static analysis of the system shows that the length ratio,and the stiffness ratio,play a major role in the nonlinear stiffness characteristics of the system.The system designed by parameter matching has quasi-zero stiffness characteristics,and its load-carrying capacity can meet the actual requirements.Finally,the third-order Taylor expansion of the dimensionless restoring force expression of the system is carried out.It is found that the error of the quantitative analysis approximate expression can be replaced by an approximate expression within the displacement limit(±3mm)of the floating slab.(3)Dynamic response and vibration isolation performance analysis of magnetorheological damper floating slab track system with quasi-zero stiffness.First,the System dynamics equation is established and dimensionalized.Then,the average method is used to solve the dimensionless dynamic equation,and the amplitude-frequency characteristic equation and the expression of force transmissibility rate are obtained.Finally,the effects of different nonlinear coefficients,vertical damping ratio,horizontal damping ratio,excitation amplitude,Cullen damping force,viscous damping ratio and input current on the dynamic response amplitude and force transmissibility rate of the system are analyzed by numerical simulation,compared with the traditional steel spring floating slab track system and the quasi-zero stiffness floating slab track system.The results show that the designed quasi-zero stiffness magnetorheological damping floating slab track system has lower initial isolation frequency than the traditional steel spring floating slab track system and the quasi-Zero stiffness floating slab track system,lower peak force transmissibility,better low frequency vibration isolation performance.(4)Simulation analysis of semi-active control for quasi-zero stiffness magnetorheological damper floating slab track system.Firstly,PID controller and fuzzy-PID controller simulation models are designed in Simulink simulation platform,and based on the magnetorheological damping floating slab track system dynamics model with quasi-Zero stiffness,the system simulation models with different semi-active control methods are built.Then,different simulation conditions are designed to determine the system simulation input excitation amplitude and frequency.Then,the control effect of the proposed control method is analyzed by simulation to verify the effectiveness of the semi-active control method.Finally,a semi-active control method of frequency + fuzzy-PID control is proposed,and its vibration reduction effect is verified by simulation.The results show that the system with semi-active control method has better vibration isolation performance at low frequency,and the effect of fuzzy-PID control is better than that of PID control.In addition,the system using frequency +fuzzy-PID control method has good vibration isolation performance outside the frequency range of 1～3 Hz.