Research On Nonlinear Dynamics Of Friction Induced Vibration In Vehicle Braking System

Vehicle braking system produces friction induced self-excited vibration,self-excited energy derived from the reduction of vehicle kinetic energy,the energy conversion to the brake system vibration process,by the brake pressure,vehicle speed,braking temperature,parts wear state,contact material properties and many other non-linear factors,the system produces strong nonlinear vibration and pollution,reduce system stability and reliability,which affect vehicle safety and dynamic response characteristics.The mechanism of vibration and noise in the braking system can be analyzed by studying the dynamic behavior of the vehicle braking system under various non-linear factors,which can provide the theoretical basis for the design and manufacture of the mechanical components of the braking system.In this paper,the basic braking part of train disc brake system is regard as the research object.On the basis of the single DOF system model,based on the research of vibration theory,considering the vibration of the brake in both vertical and longitudinal directions,two DOF braking system model of cross-suspension and friction movement at joint with brake clearance are established.The system model is dimensionally processed,and the numerical method is used to solve it.The results show that the influence of different friction models on the vibration behavior of the braking system is analyzed by the phase diagram and the time history diagram.The main contents are as follows:The dynamic analysis of the two DOF braking system with cross-suspension system is carried out.The friction motion between the brake pads and the brake disc is dominated by the Coulomb-Stribeck static friction and Dankowicz dynamic friction models.The C-language programming is used to simulate the system model.In the given system parameters,the motion of the system is convergent,and finally the steady state of motion is reached,but it can’t reflect the more complex system dynamics.The braking gap has little effect on the longitudinal and vertical vibration velocity,but it has a great influence on the vibration displacement.The larger the braking gap is,the greater the vertical and vertical vibration displacement is.The larger the initial velocity of the brake disc is the greater the amplitude of the vibration,does not affect the gate to a stable path.The friction motion between the brake pads and the brake disc is dominated by the Coulomb-Stribeck static friction model and Dankowicz dynamic friction model.The numerical simulation of the system model is carried out by C language programming.Through the phase trajectory and time history of the system,the chattering motion and the chatter-stick-slip movement law of the braking system under two kinds of dynamic friction are presented.The dynamic analysis of the two DOF braking system model with the friction motion at the joint is carried out.The friction motion at the joint is considered by the Coulomb viscous static friction model,and the friction motion pair between the brake pad and the brake disc is deduced and analyzed by using the Dankowicz dynamic friction model and the modified LuGre dynamic friction model.The system parameters of the braking system are obtained.The numerical simulation is used to simulate the brake under the action of two kinds of dynamic friction.The chattering motion and the mechanism of chatter-slip and the way to the stability path are studied.The influence of the key parameters on the system dynamics is studied.The results show that with the increase of the braking gap.There is no change in the maximum velocity of the longitudinal vibration and vertical vibration of the system,which has a great influence on the amplitude of the vibration displacement.With the increase of the initial braking speed,the initial vibration velocity of the longitudinal vibration has a great influence on the system.The stability of the path has little effect on the vertical vibration of the speed and displacement.