Rail corrugation growth-Influence of powered wheelsets with wheel tread irregularities

A multibody system model for simulation of general three-dimensional train-track interaction (accounting for frequencies up to several kHz) is used to investigate the hypothesis that rail corrugation is generated by powered wheelsets on the Swedish high-speed train X2. Part of the braking effort on the powered wheelsets is accomplished by tread braking with cast iron brake blocks. In particular, the influence of wheel corrugation, which is present because of such braking, on rail corrugation growth is studied. The numerical model uses an iteration scheme including simulation of dynamic train-track interaction in the time domain coupled with a long-term wear model. Measured wheel-rail contact forces and measured rail roughness are compared to the simulated results. Wheel-rail contact forces are considerably higher when wheel irregularities are present. However, the averaging effect from several passing wheelsets with different sets of wheel irregularities is found to give a rate of rail corrugation growth similar to the one obtained if the wheels had been completely round. The rail corrugation wavelengths are found to be explained by irregular wear due to high wheel-rail contact forces and slip caused by local rail bending modes between the two wheelsets in a bogie.