Study On Friction Flutter And Noise Mechanism Of Disk Braking System

Vehicle braking system plays a vital role in driving safety and automobile brake system is closely related to the personal safety and economic benefit for automotive products. The safety and comfort of the car arouse people’s concern with the development of science and technology. And the vibration and noise are important indexs for ride comfort evaluation. The vibration and noise can not only form noise pollution and reduce the ride comfort, but also cause the damage and failure of brake system parts and components and this may cause traffic accidents. So the study of the dynamic characteristics of vehicle braking system has important theoretical and realistic significances to improve the driving safety and ride comfort.Vehicle braking system is the object of study, aims to research and analysis friction vibration and noise generating mechanisms of braking system in the process of braking; it provides the basis for structure optimization design and material selection of braking system. According to consulting the literature of domestic and foreign about the braking system and its friction flutter, specific research objectives, contents and methods are proposed on the base of development, structure, characteristics and classification of braking system, as well as the friction braking systems research status were reviewed.Firstly, theoretical foundation of brake judder is analysis, braking system for dry friction self-excited vibration system properties is determined. Static friction model of the common coulomb friction, Dahl friction model et al, the dynamic friction model, dry friction self-excited vibration system and its corresponding friction model are expounded; it lays the foundation for modeling of the braking system for the rest of the article.Secondly, two degrees of freedom dynamics model of braking system is built, simulation analysis of different parameters on the dynamic characteristics of the brake system is done. With a model of a disc brake system as an object, a kinetic model of two degrees of freedom of self-excited vibration system is established, and numerical analysis is done. According to MATLAB, the initial braking speed, the dynamics analysis of brake pressure, stiffness and damping of the brake system is completed and try to make recommendations to improve the braking system stability.Then, the finite element mode of brake disc is built; the comparative analysis of freely modal and rotating prestressed modal are carried out. ANSYS finite element model of the brake disc is established, modal analysis of the brake discs free modal analysis and consideration of rotating prestressed are carried out, The brake disc before twelve order natural frequency and modal vibration mode are obtained, in order to provide the theoretical foundation to structure optimization design, material selection, and noise control of the braking system.Lastly, the analysis of experimental verification of the brake disc is done. The brake discs free modal experiments is conducted, the first ten order modal of brake disc is obtained, and through precision sound level meter, the noise signal is collected. Through the noise signal and modal finite element analysis of the experimental, the accuracy of the brake disk’s the finite element model and brake friction noise generation mechanism is verified.