Analysis on limiting value of rail corrugation of floating-slab track based on wheel/rail multi-point contact

Abstract

In the metro railway, the rail corrugation will aggravate the dynamic wheel/rail interaction, reduce the service life of the components of the vehicle and the track, increase the cost of maintenance and workload, and even threaten the vehicle running safety. It is an effective method for eliminating the adverse effects of rail corrugation to determine the limiting value of rail corrugation and grind the rail without delay. In order to determine the limiting value of rail corrugation for floating-slab track (FST), the vehicle-FST coupled dynamic model is developed, based on the vehicle-track coupled dynamics theory, to analyze the influences of rail corrugation of different levels on the dynamic responses of vehicle-track coupled system. Then the limiting value of rail corrugation is proposed from the aspects of the vehicle running safety, the vehicle running comfort and the dynamic performance of vehicle-track coupled system. In the model, the vehicle is treated as multi-rigid-body system of 35 degrees of freedom and the suspension systems are modelled by linear or nonlinear spring-damper elements. The rails are simplified as Euler beams. The vertical motions of the floating slabs are described by elastic thin plate, and for the lateral motions and rotations in the horizontal plane, the slabs are treated as rigid bodies. The mechanical behaviors of the fasteners and steel spring are described by linear spring-damper elements. In order to more accurately descript the wheel/rail interaction, the improved Kik-Piotrowski method is used in the vehicle-FST coupled dynamic model to consider the wheel/rail multi-point non-hertz contact. The results show that, the rail corrugation will observably aggravate the dynamic wheel/rail interaction, especially in the case that the wave length of the rail corrugation is below 70 mm. With the wave length of the rail corrugation decreasing or the wave depth of the rail corrugation increasing, all of the vertical wheel/rail forces, the lateral wheel/rail forces, the derailment coefficient and the reduction ratio of wheel load are worsened. The influences of the wave length and wave depth of the rail corrugation changing on the reduction ratio of wheel load is the most obvious. When the wave length of the rail corrugation is constant and the wave depth is creased, the reduction ratio of wheel load will exceed the safety limit before the other indicators over the limits. In the case that the train is running with the speed of 80 km/h, when the wave length of the rail corrugation reaches about 0.05 m, its wave depth should be controlled to be below 0. 2 mm. Besides, when the wave depth of the rail corrugation reaches about 0.1 mm, its wave length should be controlled to be more than 30 mm.