Chatter Analysis Of Railway Vehicle Disc Brake System

Disc braking device, as the main brake rigging, is widely used in high speed trains. In the braking process, the unwanted high-frequency vibration is generated by friction between the brake discs and brake pads. The vibration will not only do destruction to the equipment of car body, bogies and brake system, but also reduce the running stability and passengers ride comfort. And this high-frequency vibration noise will make noise pollution around the railway worse. So, to solve the problem of the chatter has vital significance for the development of high-speed and heavy-load railway. How to analyze and suppress the vibration of the disc brake system are studied in this thesis, the contents are as following.The first chapter is the introduction part. The research background, domestic and international development, disc braking system, failure of disc braking system, generation of chatter,chatter analysis and research status are all introduced. Finally a brief introduction to the content of this study is given.In the second chapter, the mechanical model of friction is described, from awakened ideal type to speed-dependent models. Railway vehicle vibration analysis, phenomenon of friction chatter, vibration analysis of railway vehicle, and the mechanism of brake chatter are all described, finally several solutions about nonlinear problems are summed up.Under the principle of disc braking system, as brake disc is considered as fixed rigid, the movement of brake pads is analyzed in the third chapter. A single freedom dynamic model is established, and a reasonable model of friction force is chosen as a friction system. Using analytical methods, analytical solution of pure sliding condition of the system is calculated and analyzed the stability of the system. Finally studied the various influence factors on the system.In the fourth chapter, the brake discs are considered as a mass, and a parallel of two degrees freedom dynamic model is built taking the interaction between brake disc and brake pads into account, and a reasonable amount of frictional force model is chosen as a system of friction, it shows that critical speed exists in this system, and that the vibration will be gradually weakened when the speed is above the critical speed, otherwise, the phenomenon of chatter will be produced. By using numerical simulation methods, the influences different braking speed and brake pressure have on the system are analyzed, taking the influence of track irregularity in the operation of trains into account. Using SIMULINK for modeling and simulation, the train movements of different braking original speeds and braking pressures are analyzed.In the fifth chapter, a three-degree freedom dynamics system is established with considering about the effect of orbital excitation on the brake device, the contact deformationbetween the brake pads and brake disc, and brake pads may appear reversed in braking process. And the brake pad movement condition of the tangential, lateral and torsion angles are analyzed under different braking condition, it proves that the friction-negative slope phenomenon is not the only factor in the production of chatter.