Effect of uneven wear on the stability of friction braking system in high-speed train

The frictional interface in high-speed train braking systems is subjected to prolonged exposure to high loads and frequent friction, leading to noticeable macroscopic surface alterations. Uneven wear, as the primary manifestation change, is characterized by a discernible inclination angle between the friction block and the brake disc. In this study, a three-dimensional numerical model incorporating six degrees of freedom is developed to investigate the influence of wear-induced inclination angles on the stability of the disc-block coupling system. Modal analysis and practical experiments are conducted to validate the accuracy of the model. The analysis reveals that both tangential and axial inclination angles significantly affect the system's stability, with the system demonstrating heightened sensitivity to variations in the axial inclination angle. These angles induce variations in the contact area, subsequently leading to changes in the friction coefficient and contact stiffness. Decreasing the stiffness ratio between the normal and tangential directions proves advantageous in enhancing the system's stability and reducing the tendency for unstable vibrations within the friction system. Similarly, increasing the friction coefficient yields similar effects. Besides, time-domain analysis of acceleration signals obtained from both the numerical model and practical experiments indicates that an escalating inclination angle results in unstable vibration behavior, potentially leading to system instability. Therefore, understanding and controlling wear-induced inclination angles are essential for maintaining the stability and performance of high-speed train braking systems.