Long-term evolution mechanism of the rail weld irregularity in metro lines based on the wear theory

Abstract

This paper aims to investigate the formation and long-term evolution of the rail weld regularity in metro lines on the basis of the rail wear. To this end, a field measurement was first carried out to acquire the longitudinal geometrical characteristics of the rail weld irregularity. Based on the experimental data, the initial rail irregularity and hardness softening are regarded as two principal reasons that result in the formation of rail weld irregularity. In order to illustrate the causes, a hybrid theoretical model was then developed and well validated by the experimental data, which includes a typical 2-demensional vehicle-track coupled model, a nonlinear wheel-rail contact relationship and a rail wear model. By means of the validated model, the long-term evolution process of the rail weld irregularity was demonstrated and the influences of the axle load, running speed, hardness difference and long-wave length on the evolution characteristics of the rail weld regularity were studied.