Study On The Occurrence Propensity Of Brake Squeal Of A Railway Axle-discs Brake System

With the development of the urbanization, the high-speed railway plays a more and more important role in the urbanization development process. Brake squeal generated by a railway vehicle disc brake system seriously pollutes the living environments. At the same time, it indicates that a strong self-excited vibration occurs on the brake system, which probably leads to invalidation or destroy of the brake system.So, it is significant to study brake squeal and self-excitation vibration characteristics of disc braking systems for high-speed railway trains.In this paper, the author established a3D model of a high-speed train brake system, which includes a wheelset and three disc brake units. Abaqus package was applied to make the complex eigenvalue and transient dynamic analyses of the disc brake system. If the real part of a complex eigenvalue is positive,the corresponding mode is unstable,which may result in squeal.According to the transient dynamic analysis, the instability frequency of the brake system is obtained. In this thesis, The influences of the brake disc structure, friction coefficient, rotation speed of brake disc, elastic modulus of the brake disc on brake squeal are discussed.Based on the numerical simulation results, the following conclusions can be drawn:1、The brake disc structure such as disc thickness, friction pad thickness and the cooling pad have a distinct influence on the occurrence of brake squeal.It is feasible to promote motion stability of disc brake systems and to suppress squeal by changing the brake disc structure for disc brake systems. The larger the contact surface area, the more easily the self-excited oscillation occurs.2、The coefficient of friction has a heavy influence on the occurrence of brake squeal.With the friction coefficient increasing,the positive real part values of the complex eigenvalues of coupling modes increase and more modes with positive real parts arise. The transient dynamic analysis shows that the corresponding vibration amplitude increases.That suggests that the propensity of squeal occurrence will increase.3、With the rotation speed of the brake disc increases, a change in the occurrence propensity of the braking system is found. The transient dynamic analysis shows that the effect of a rotational speed of the braking axle has a little influence on the propensity of squeal occurrence.4、With the increasing of the elastic modulus of the brake lining, the occurrence propensity of brake squeal of the brake system increases and the dominant frequency of brake squeal increases significantly.5、The occurrence propensity of brake squeal of the brake system decreases then increases with the increasing of the elastic modulus of the brake disc.