A method for modelling infinite long track
It is known that the rail vehicles operate on a continuously infinite long track, and subjected to a variety of periodic excitations due to the discretely supported track system. In order to represent the track more realistic, the time-domain coupled vehicle/track dynamic model consisting of a typical high speed vehicle and a flexible slab track model is put forward, in which a track replacement method for modelling the track as an infinite long track is proposed. The main hypothesis is to move the vehicle to a new track model after the vehicle passes over a considered track length on the old track. By repeating this iterative procedure, the limitation of the finite-length track is thus avoided. The least square criterion is employed each time to eliminate the initial disturbances of new track owing to initial problems caused by the track replacement. The validity of proposed method is demonstrated by comparing the rail/wheel forces to those obtained from conventional excitation model, namely, moving mass model and moving irregularity model. Consequently, the track replacement method is applied to investigate the steady-state responses of a high-speed vehicle due to discrete rail pads. The results via simulation and field tests suggest that the wheel/rail system would fluctuate severely as the sleeper passing frequency approaches the coupled wheel/track vibration frequency (P2 resonance frequency).