Thermal Load Analysis Of Wheels For40T Axle-Load Freight Car

With the development of technology and economic, chinese freight cars are on the way to heavy haul.As one of the vast countries abundant in resources, chinese bulk cargo such as iron ore and coal must rely on railway transportation to circulate. The rapid growth of economic pull the volume of goods, if the capacity is insufficient, it can’t meet the requirement of growth of volume.Heavy haul transportation can make up for the defect of lack of capacity and reduce transportation cost. The economic value and benefit from heavy load transportation are very obvious. Now in China, the axle-load of general-purpose freight car is23t, and the axle-load of special-purpose freight car for heavy haul is25t. The heavy haul freight cars developed by China have been exported abroad, including the40t axle-load freight car for Australia. As the limit of facilities such as locomotive, vehicle and track,40t axle-load freight car has not been used on chinese internal lines, some departments are doing some research on the relevant technology.The great increase of axle-load of freight car can lead to the increase of wheel-rail force and wear, also the deterioration of wheel thermal load while braking. These problems have serious impacts on the life of line, vehicle and equipment, also they are severe test to the operation quality and safety performance of the train. If these problems could be resolved, it is helpful for railway vehicle to promote the comprehensive performance completely. In this paper, taking40t axle-load ore gondola car as a reference, the wheel thermal load of tread braking based on40t axle-load freight car was explored and analyzed. It included the change of thermal load and its impacts on the strength of wheel.First of all, the dynamics calculation model of40t axle-load freight car was established according to the relevant parameters. With the change of speed, its dynamics performances on tangent and curve were calculated and analyzed. The result shows that the largest business running speed of40t axle-load freight car should not be above80km/h.After the suitable speed had been confirmed, the thermal load of the wheel was analyzed. The content included the temperature fields and thermal stress fields of wheel under emergency braking and grade braking. The result shows that the variation trends of temperature fields under two conditions are different, and the variation of thermal stress fields always follow the related temperature fields. The high temperature often occurs on tread, and the high thermal stress occurs on web plate and tread easily. Meanwhile the fluctuations of triaxial stress are not same on different weak positions. On the other hand, under four load conditions, the impact of thermal load on the static strength of wheel was studied further. The result shows that the static strength of new wheel can meet relevant requirement, but wear wheel can not meet relevant requirement under some conditions of emergency braking, as its wheel rim is not thick enough. Furthermore, the change states of static strength on tread and both sides of web plate were analyzed, and the impact of thermal load on different positions was obtained. Under the thermal and mechanical load, the fatigue strength of wheel was evaluated finally. Regarding fatigue strength, it is found that new wheel can meet the requirement, but some positions on web plate of wear wheel surpass the requirement.In this paper, the dynamics of40t axle-load freight car was calculated, and the impact of thermal load on wheel of40t axle-load freight car was deeply researched. For40t axle-load freight car, this research is a good reference for its use and application in China.