Friction-induced stick-slip vibration characteristics and tribological behavior of high-speed train braking interfaces under various external force excitations

During low-speed braking phases of high-speed trains, friction-induced stick–slip vibration (FISSV) is frequently observed, primarily excited by strong interfacial friction, which generates harsh friction noise. The intense vibration also causes abnormal wear and even detachment of friction blocks, leading to service failures that threaten operational safety. Therefore, it is essential to investigate the characteristics of FISSV and the associated tribological behavior at the braking interface under strong friction, and, on this basis, to propose effective methods for FISSV regulation. The braking force, as the external force applied to the brake friction pair, dynamically adjusts according to the operating state of the train. This variation results in different FISSV characteristics and friction wear behaviors at the interface. However, few studies have been reported in this area. This research aims to address this gap by systematically elucidating the FISSV characteristics and friction-wear behavior of high-speed train braking interfaces under different loading conditions through an integrated experimental and numerical approach. Experimental investigations were carried out under four distinct load levels utilizing a custom-designed multifunctional friction wear testing machine. Concurrently, a finite element methodology incorporating dynamic-wear coupling was developed within the ABAQUS to model the evolution of contact pressure distribution and wear patterns. The findings reveal that applied load exerts a substantial influence on interfacial contact pressure distribution and wear mechanisms, with elevated loads resulting in pronounced pressure concentration at the leading edge of the friction block, resulting in severe eccentric wear (EW) and more intense FISSV responses. With increasing load, the vibration intensity, displacement amplitude, and vibration period of the system all increase remarkably, while the adhesion stage lasts longer. This study reveals the mechanism by which load influences FISSV behavior by modulating interfacial friction and stress distribution, providing theoretical guidance for vibration control and structural optimization of high-speed train braking systems.