Effect of sleeper pitch on rail corrugation at a tangent track in vehicle hunting

The effect of sleeper pitch on the initiation and development of rail corrugation at tangent track is investigated using a numerical method in vehicle hunting. The numerical analysis considers a combination of Kalker's rolling contact theory with non-Hertzian form, linear frictional work model and the dynamics model of a half railway vehicle coupled with a tangent track. Kalker's theory is modified. The half vehicle has a two-axle bogie and doubled suspension systems. It is treated as a full dynamic rigid multi-body model. In the tangent track model, an Euler beam is used to model each rail, and the backward moving discrete supports of the rails are considered to simulate the action of the discrete sleeper supports on the wheels/rails in rolling contact, when the train running on the track. The sleepers are treated as rigid bodies and the ballast bed is replaced with equivalent mass bodies. The effect of the discrete sleeper supports on the normal loads of the wheels/rails is analyzed at different speeds. The easily excited resonant frequencies of the wheelset and the track at different speeds are investigated in detail. In order to find the conditions necessary for rail corrugation occurring at the tangent track through numerical simulation, the vehicle hunting at higher speed is caused by setting the appropriate initial displacement condition of the vehicle system. The numerical results show that when the yaw angle of the wheelset reaches its maximum value in the vehicle hunting the lateral creepage of the wheel and rail oscillates at sleeper passing frequency and higher track frequencies. Therefore, rail corrugation due to wear initiates with several frequencies including sleeper passing frequency, and grouped near the peaks of the wheelset yaw angle. With increasing passage number of the vehicle in hunting, the corrugation became serious and also extended further along the rail. (C) 2008 Xuesong Jin. Published by Elsevier BY. All rights reserved.