长大坡道紧急制动工况下货车车轮踏面温升和热应力影响规律研究

Temperature and Thermal Stress Behavior of Freight Wagon Wheel Tread Under Emergency Brake Conditions for Long Downhill Ramps

摘要:

建立一种兼顾计算精度与效率的二维踏面制动摩擦热机耦合有限元数学模型，综合考虑热机强耦合的高精度与弱耦合的高效率特性。研究线路坡道、车辆载荷与轴重、紧急制动初速度、紧急制动减速度和环境温度等因素对车轮踏面最高温度和最大热应力的影响。结果表明，线路坡度每增加3 ‰，车轮踏面最高温度线性增加约4.15 ℃，最大热应力线性增加约8.18 MPa；载荷每轴增加1 t，最高温度线性增加约7.19 ℃，最大热应力线性增加约14.29 MPa；制动初速度每增加10 km·h^-1，最高温度近似线性增加约31.21 ℃，最大热应力近似线性增加约59.77 MPa，并且达到最高温度/应力的时间随速度增加而呈非线性延长；减速度每增加0.2 m·s^-2，最高温度近似线性增加约16.12 ℃，最大热应力近似线性增加约31.67 MPa，同时达到最高温度的时间呈非线性缩短；环境温度降低时，踏面最高温度值呈减小趋势，但对最大热应力的影响较小。研究结果为长大坡道列车运行的热安全性评价及优化设计提供了量化数据支撑和技术参考。

Abstract:

A two-dimensional tread braking thermo-mechanical coupled finite-element mathematical model is established that balances computational accuracy and efficiency， integrating the high accuracy of strong thermo-mechanical coupling with the high efficiency of weak coupling. The effects of track gradient， vehicle load and axle load， initial emergency-braking speed， emergency-braking deceleration， and ambient temperature on the maximum tread temperature and peak thermal stress of the wheel are investigated. The results show that for every 3 ‰ increase in track gradient， the maximum wheel-tread temperature increases linearly by approximately 4.15 °C， while the maximum thermal stress increases linearly by about 8.18 MPa. For each 1 t increase in axle load， the maximum temperature increases linearly by approximately 7.19 °C and the maximum thermal stress by about 14.29 MPa. For every 10 km·h?1 increase in initial braking speed， the maximum temperature increases approximately linearly by about 31.21 °C and the maximum thermal stress by about 59.77 MPa； meanwhile， the time required to reach the maximum temperature and stress increases nonlinearly with speed. When the deceleration increases by 0.2 m·s?2， the maximum temperature increases approximately linearly by about 16.12 °C and the maximum thermal stress by about 31.67 MPa， while the time to reach the maximum temperature decreases nonlinearly. As ambient temperature decreases， the maximum tread temperature shows a downward trend， whereas its influence on the maximum thermal stress is relatively small. These findings provide quantitative data support and technical reference for thermal safety evaluation and optimized design of train operations on long and steep gradients.