Excitation frequency, fastener stiffness and damping, and speed of the moving harmonic load on the dynamic response of the track structure

Abstract

The dynamic response of a track structure under a uniform-speed moving harmonic load is researched according to dynamic response characteristics of a periodic structure under moving harmonic load in the frequency domain. The track was assumed as a simple Euler beam model periodically supported by continuous discrete point, and mathematical model of the dynamic differential equation of vertical vibration for the track structure is built. Then, the analytical equation for the dynamic response of any point on the track structure is concluded in the frequency domain for the following research. The dynamic responses of the track structure under the uniform-speed moving harmonic load are investigated using the theory of infinite periodic structure. Finally, the effects of excitation frequency, fastener stiffness, fastener damping, and speed of the moving harmonic load on the dynamic response of the track structure are studied. Results indicate that the response peaks of the rail under moving harmonic load occur near the excitation frequency, and the dynamic response decreases rapidly in the area far from the excitation frequency. The response peaks of the rail will move slightly toward a high frequency with the increase in the excitation frequency. The increase in the fastener stiffness will lead to improvement of the dynamic response of the rail in the nonresonant region at a high frequency, equivalent to the high rigidity of the rail fastener and intense vibration of the rail. The changes in fastener damping exert no significant effect on the resonant peak and peak bandwidth of the system. The fastener damping plays a significant role in restraining the vibration at a high frequency. The strong vibration of the track structure can be effectively controlled by an increase in the damping.