A comparative study of WSP control methods: Effects on wear and RCF evolution in railway wheels

Wheel Slide Protection (WSP) controller is a critical component in modern railway trains, which is designed to mitigate wheel sliding behaviours while minimising wheel/rail interface material degradation at braking operations. This study presents a novel vehicle-track coupled dynamics model, incorporating variable friction conditions and a non-Hertzian wheel/rail contact model to more accurately reflect the real-world scenarios. Three types of on-board WSP controllers are integrated into this compositive model: (i) re-adhesion controller, (ii) sliding-mode controller, and (iii) PID-based controller. In addition, a prediction model for long-term wheel tread wear and rolling contact fatigue (RCF) evolutions is introduced utilising real-time calculations of non-Hertzian wheel/rail interactions. The effects of different WSP control algorithms on wheel tread wear and RCF progression are investigated through the extensive numerical simulations. The results indicate that the sliding-mode and PID-based controllers outperform re-adhesion controllers in reducing wheel/rail longitudinal interactions and vibrations, and further contributing to smoother operations. Moreover, it is shown that lower WSP control thresholds significantly reduce wheel tread wear and RCF development in contrast to the higher thresholds which exacerbate these issues. Interestingly, while sliding-mode and PID-based controllers reduce vibrations more effectively, they also result in higher wear and RCF growths when compared to re-adhesion controller, particularly with a high control threshold. The findings provide a theoretical foundation for optimising WSP control systems in railway operations with the goal of enhancing durability, reducing maintenance costs, and improving overall train performances.