Analysis Of Influencing Factors On Disc Brake Squeal

With the development of the automobile industry, car as a tool,has become more and more popular. However, we need to point out that the convenient life accompanied by the car is influenced by the noise pollution and the noise pollution has become one of the most serious thing in the modern world, we should never ignore it in a public place. According to the statistics, the city's transportation noise can account for 75% of all kind of noise, and the automotive noise can account for 85% transportation noise. The brake squeal is the key part of the automotive noise. Noise pollution has many bad sides, it can disturb people's normal life and work, influence people's talking and thinking, make people feel uncomfortable and work under a low efficiency, scatter people's attention, and the most serious thing is that the noise can even damage people's hearing and healthy, make the people's digestive system, circulatory system and the endocrine system become bad. With the development of transport industry, automotive noise including brake noise has become a problem that we have to face. So, in order to improve vehicle's harshness, many automotive companies in the world have made a stricter noise control standard and take it as a important research direction.Disc brakes and drum brakes are two major types of brakes. Disc brakes has these advantages such as: thermal stabilization, enhydrous stabilization and easiness in changing or servicing the disk brakes, so we can see that disc brakes has a considerable market prospect. This paper aim at the configuration of disc brake assembly, use complex eigenvalue method to analyse the vibration feature of disc brakes, find out which parameters will have an important influence on brake stability and finally put forward some measures to reduce brake noise.This paper can be divided into six chapters, the major contents are followed below:The first chapter described the influences of brake noise on people's life and pointed out that how to reduce brake noise is a problem that we must face in modern society. Then the chapter discussed the classification and influences of brake noise. We also reviewed on the growing history, status in quo and future trend of brake squeal research. We also illustrated some theory model of brake noise, such as single degree-of-freedom model and multi-degree-of-freedom model. We also mentioned experimental methods and finite element methods. Finally we introduced the content and steps of this paper.The second chapter introduced describes the composition, structure and principles of disc brakes, enumerate the types of disc brakes and its advantages. Finally, we also introduced the connection of vibration and noise, it is the key cause that why disc brake produces noise.The third chapter introduced some theories used in this paper, such as finite element theory, contact theory and complex eigenvalue method. The finite element method is usually used in the computational mechanics and computational engineering. Contact problems are very difficult and important in many technical fields, so contact theory model is developed based on experience and experiment. Complex eigenvalue theory is the most important theory of brake noise analysis. We use this theory to judge which frequencies are the most unstable. Finally, we introduced some software such as CATIA V5 , ABAQUS and so on.The fourth chapter introduced how to build disc brake model. Then we use abaqus to analyse its mechanics and mode characteristic. Building disc brake model included the collecting of disc material, the establishing of disc's CAD model, the establishing of finite element model and the analysis of the model. Finally, we got the unstable frequencies of the disc and the corresponding vibration mode map.The fifth chapter introduces some measures to reduce brake noise. According to the model used in the paper, we studied several parameters to find out which parameters play the most important role in the brake stability. Finally, we discovered some parameters to reduce brake noise, changing these parameters will not affect the brake performance.The sixth chapter is the summary. Describe the main work and the conclusion we obtained, as well as the future research direction . We took the disc brake system as a whole thing to study, took into account the connecting between the pad and the rotor, used the complex eigenvalue to calculate some unstable frequencies. Because the disc brake system is simple, the results obtained from the analysis will not have the same as the real condition. So, in future research , we still need to study a more complex disc brake model and consider some other factors such as temperature and humidity. Finally, we also need to do some experiment to validate the results. In short, brake noise is a very complex problem in engineering fields. Finite element method is an effective method. With the development of modern mechanics, computational mechanics and computer, the finite element method will be used more and more widely.