Preliminary Study On The Prediction Of Wheel Wear

Wheel/rail wear is one of the serious problems in railway engineering. Several methods have been used to relieve the profile evolution due to wear, such as developing new material, optimazing wheel/rail profile to decrease contact stress, improving the structures of track and vehicle to reduce the dynamic effect. With the increase of train speed and axle load, the interaction between wheel and rail becomes fierce and the wear phenomenon of wheel/rail shows a tendency to increase. The railway transportation security is directly endangered. A great deal of money is spent every year by railway transportation companies on the maintenance and replacement of wheel and rail. Therefore investigations into wheel wear mechanism and its root causes are very important to solve this problem.The main research work in the present thesis is as follows:(1) The studies on wheel wear in the past in the world are reviewed. The significance of the research on wheel wear is indicated.(2) A wheel wear model is put forward. It considers a combination of the Archard material wear model, the Kalker's non-Hertzian rolling contact theory to be modified and the coupling dynamics of rail vehicle and track in the vertical and lateral directions.(3) Two wear superposition methods for accumulated wear calculation are developed. The first method considers using the result of a step rolling contact calculation to obtain the wear on the wheel circumference after a cycling. The second one uses the reulst of rolling contact calculation of a contact patch in the longitudinal direction. Compared to the first method the second one is much time-consuming, but the results obtained by it are more accurate.(4) The calculation model uses three smoothing methods for the numerical accumulated wear data, which are, respectively, the five-spot triple smoothing, spline smoothing and super smoothing. Their influence on the calculation results of the wheel wear is investigated in detail. It is found that the super smoothing method is more reliable and even somewhat more efficacious than other two methods. (5) The evolution of wheel profile due to wear is analyzed in the sharp curves. A conclusion can be drawn from the numerical results that the wear of the leading wheelset is more severe than the trailing wheelset in the same bogie. The wear of the wheels on the outer rail is more serious than wheels on the inner rail. The phenomenon agrees with the site situation.(6) The effects of axle load, vehicle speed, material hardness and structure parameters on the wheel profile wear are investigated. The results obtained show that the primary suspension stiffness has a great influence on the wheel wear. For the same suspension stiffiness the wheel wear becomes severe with the increase of axle load. The wear ammount increases with the growth of vehicle speed in straight line. At the balance speed of the vehicle in the curving the wheel wear is milder than at other speeds. And the wear decreases with the increase of material hardness.