Although preliminary understanding of the wheel/rail adhesion re-rising characteristics in the speed range of 200-400 km/h has been achieved,the distribution law of the maximum wheel-rail adhesion force coefficient(adhesion coefficient)at different speeds and adhesion stages remains unclear,limiting the improvement of the train braking adhesion efficiency at the 400 km/h speed level.Using a 1:1 scale high-speed wheel-rail test rig,the distribution of the wheel-rail adhesion coefficient during large-slip braking under water-mediated conditions was obtained for speeds ranging from 50 to 440 km/h.The results show that:a consistency exists between the braking adhesion coefficient at the first peak(point A)and the traction adhesion coefficient during large-slip loading;the braking adhesion coefficient at the second peak(point B)is approximately 2-3 times that of point A,and exhibits a near-linear decreasing trend with increasing speed;the braking adhesion coefficient at the third peak(point C)appearing during large-slip unloading is significantly higher than that of point B,exceeding it by approximately 1 time,and decreases with increasing speed in the range of 300-440 km/h.The superior adhesion performance at point C plays a key role in improving train braking performance and stability.Under low roughness wheel-rail contact surfaces and water-mediated conditions,the braking adhesion coefficient is lower than that under medium roughness conditions,and the"unloading peak"(point C)is less likely to appear during large-slip unloading,which will significantly affect train braking efficiency and safety.
关键词
黏着再上升/加卸载控制/蠕滑率保持/表面粗糙度/黏着力系数
Key words
Adhesion re-rising/Loading and unloading control/Maintaining creepage/Surface roughness/Adhesion force coefficient
万方数据