Investigation on the braking vibration behaviours of a high-speed train considering the perforation-induced dynamic COF

The tribological behaviour of the block–disc interface plays a critical role in braking dynamics, particularly in friction-induced vibration (FIV). In this work, small-scale block–disc tests were conducted to characterise dynamic coefficients of friction (COF) for unperforated and perforated friction blocks, showing that perforations consistently reduced COF fluctuation amplitudes. These results were then used to further analyse and evaluate their effects on the vehicle system dynamics. As a result, a spatial vehicle–track coupled dynamic model incorporating flexible wheelset and brake components was developed to analyse the braking behaviour of a high-speed train. And then, a co-simulation approach was designed to integrate the dynamic COF directly into the friction force calculation while accounting for vehicle–track interaction. The proposed approach was validated using field test data. The results demonstrate that dynamic COF produces significantly stronger system responses than static COF assumptions, including substantially higher wheel–rail creep forces and elevated brake vibrations. Additionally, the comparative analysis showed that as the perforation size increased, the brake system's vibration response and the wheel–rail interaction intensity decreased. These findings highlight the importance of dynamic COF modelling and demonstrate that controlled surface perforation is an effective strategy for mitigating FIV.