Research On Friction Vibration Of Three-Body Disc Brake System Including Hub Motor

The braking process of a vehicle is a very complex tribological phenomenon.Its random dry frictional multi-frequency and multi-amplitude vibrations often cause vehicle chatter,jitter and abnormal noise during braking.In severe cases,it can affect the safety of vehicle braking and even induce traffic accidents.Under actual braking conditions,the friction interface of the brake pair often contains third-body particles from the outside or due to disc and pad wear,and because the braking process of the vehicle is a strongly non-linear change process,the existence of particles has the potential to make a huge impact on the vibration characteristics of the brake system.So the main research contents and conclusions of this article are as follows:(1)The dynamic model of the brake system with in-wheel motor and its differential equations are established.The numerical analysis method is used to study and analyze the influence of the structural parameters of the brake system with in-wheel motor on the vibration characteristics of the system.It is found that the brake system with in-wheel motor has complex bifurcation chaos characteristics under low-speed braking conditions,and under low-speed braking conditions,the braking pressure and the proportionality coefficient γ have a very important influence on the bifurcation and chaos characteristics of the brake system.(2)Based on the ZMC contact model,a two-body coupled friction model suitable for nonlinear vibration analysis of a brake system is established.Through analysis,it is known that under two-body contact,the gap between the discs will decrease non-linearly with the increase of the total braking pressure,and its decreasing rate gradually decreases;the actual contact area between the discs and pad will increase linearly with the increase of the total braking pressure.(3)Based on the H model,a three-body coupling friction model suitable for the nonlinear vibration analysis of the brake system is established.Through analysis,it is known that in addition to the relative sliding speed,the braking pressure and the average particle radius also have a very important influence on the three-body coupling friction coefficient.With the increase of braking pressure,the total friction coefficient of the three-body coupling system increases first and then decreases;as the average particle radius increases,the total friction coefficient of the three-body coupling system increases non-linearly trend.(4)Based on the established three-body coupled friction model and the brake system dynamic model with a hub motor,the effects of particles are analyzed.Through analysis,it is known that with the change of the average particle radius,the vibration form of the brake system is a complex transition between chaos,double period and single period.In addition,it was also found that with the increase of the average particle radius,the bifurcation and chaos characteristics of the system regarding the braking pressure and the proportionality coefficient γ also changed greatly,and the area where chaotic vibration occurred has been decreasing.When the average particle radius exceeds a certain value,the system only vibrates in the form of single cycle or double cycle.