Calculation model of the vehicle – CRTS II coupling system with symplectic method

Abstract

In this paper, the vibrations of the vehicle – CRTS II (abbreviation for China Railway Track System II) slab ballastless track vertical coupling system for high-speed railways were studied. Based on the structural characteristics of the CRTS II ballastless track, a dynamic model of the CRTS II ballastless track was established, and an effective calculation method was applied to determine the frequency response of the system. In this method, the track structure was divided into innumerable substructures by fastener spacing. Four substructures under the wheel–rail force were chosen as the subject while the transmission of simple harmonic waves in such track substructures were solved using the symplectic method. In addition, the transfer function between the track irregularities and the dynamic response of the coupling system was solved, and with these results, the coupling system’s frequency response was obtained. Furthermore, the method was proven accurate and efficient (see examples in this paper). The effects of track parameters on the coupling system’s frequency response were also studied, which provide a basis for the optimization of the design of the CRTS II ballastless track. As shown in the study, with respect to the desired track geometry and dynamic displacement, the application of the fastening system featuring low stiffness and large damping can effectively reduce the frequency response of the coupling system, while the elastic modulus and damping of the cement asphalt mortar exert the least impact on the frequency response. In addition, the subgrade stiffness shall be managed at an appropriate level, and greater subgrade damping can effectively minimize the coupling system’s vibrations.