Research On Lateral Dynamic Characteristics Of Floating Slab Track

Floating slab track (FST) is a new-type track which has high efficiency of vibration isolation. The mechanism of its vibration isolation is to add a system of floating slabs and springs which has low natural frequency between rails and ballast bed, so that the transmission of rail-wheel interaction to the base is isolated. Meanwhile, the rails absorb some energy which should transfer to the base and the vibration of rails increases sharply. Especially for the curved track, short and medium floating slabs which have small moment of inertia can lead to large lateral deflection of rails and affect the safety of train operation. Thus, the lateral vibration of FST needs to be modeled to study the lateral responses of floating slabs and rails under the lateral rail-wheel interaction, and to evaluate the safety of vehicles operation according to the rail and wheel contact position.The analytical model of lateral vibration of FST includes rails being treated as infinite Euler beam, rail pads being treated as linear springs and torsion springs, floating slabs being treated as rigid body, and slab bearings being treated as linear springs. The lateral rail-wheel interaction forces are applied on the rails. The resilient force in rail pads and slab bearings and the lateral response of rails and floating slabs are calculated by dynamic stiffness method.The finite element model of FST is modeled in ANSYS. The rails are modeled in BEAM4 elements, floating slabs are modeled in SOLID45 elements, rail pads and slab bearings are modeled in COMBIN14 elements. Modal analysis and harmonic analysis are made to verify the analytical model. Furthermore, the effects of parameters of FST on the responses of floating slabs under interaction forces of single wheel pair and double wheel pair is studied, and the responses of rails under the rail-wheel interactions in different numbers and interaction positions of wheel pairs are compared.The analytical model of the lateral vibration of FST is developed and verified by the finite element model. Under interaction forces of single wheel pair, the lateral response of rails would decrease as the lateral stiffness and torsion stiffness of rail pads increase; the lateral responses of rails would increase as distances among rail pads increase; the lateral response of rails would decrease as the sizes (i.e. lengths, widths and heights) of floating slabs increase. Increasing the lateral stiffness of slab bearings can increase the resonance frequencies increase, which can only decrease the response of rails in low frequency, but the attenuation rate will be slower. Under interaction forces of multi wheel pair, the responses of rails are similar to that of single wheel pair, but several peaks appear due to multi excitation, and the attenuation is not evident. After comparing results of different number of wheel pairs, it is cleared that at least two wheel pairs are needed to acquire accurate lateral responses of floating slab, and the superposition effect of two neighboring wheels pairs mainly affects the responses of rails.This Thesis studies the lateral vibration of FST under the rail-wheel interaction. This study can provide a basis of vehicle operation safety and riding comfort for FST, and provide some references for modeling vehicle-track lateral coupling system.