A numerical train–floating slab track coupling model based on the periodic-Fourier-modal method

A numerical model based on the periodic-Fourier-modal method is proposed for the dynamic analysis of a train-floating slab track coupling system with random track irregularity. In the model, each vehicle of the train is modeled as a multiple-degree-of-freedom vibration system consisting of one car body, two bogies, four wheelsets, and two groups of spring-damper suspension devices. The floating slab track is modeled as a periodic-infinite structure with discrete supports and discontinuous slabs. Linear springs are used to couple the train and the track. In order to establish this numerical model, an efficient periodic approach named periodic-Fourier-modal method for solving the dynamic response of the floating slab track under a harmonic moving load is first developed. Based on this, a strategy is then proposed which can couple the moving train to the track with random irregularity and express the wheel–rail force as a superposition of a series of harmonic loads. With the solved wheel–rail force, the vehicle response can be directly calculated through vehicle dynamics, while track response can be calculated through the principle of superposition and the reuse of the initially proposed periodic-Fourier-modal method. Using this train–floating slab track coupling model, the solution of the dynamic response of the infinite track can be transformed to perform only within a single periodic range, which can save the calculation time significantly. The numerical results of the Beijing subway, based on the proposed model, are discussed in detail, and some important conclusions are drawn.