Stiffness deterioration rule of elastic iron plate of high-speed turnout and its influence on speed increase

A tracking test was conducted to evaluate the damage development and stiffness evolution of the elastic iron plate of high-speed turnouts. Based on the measured data, a vehicle-turnout coupling dynamics calculation model was established, and the influence of stiffness deterioration of the elastic iron plate on the vehicle-turnout dynamic characteristics was analyzed. The adaptability of high-speed turnout to the further increase of operation speed under deteriorated stiffness was studied. Analysis results show that with the long-term use of the elastic iron plate of high-speed turnout, a series of damages appear, including rubber aging, cracking, separation, falling off, and rusting of iron components. For both the ballast and ballastless turnouts, the ratios of dynamic stiffness to static stiffness of iron plates change slightly, whereas the static stiffnesses increase. The static stiffness of the iron plate of ballast turnout shows evident changes at the initial stage, and the growing rate can exceed 60% after 3 years of service. The static stiffness of the iron plate of the ballastless turnout in the general area can increase maximum by 30%. The stiffness change is smaller than that of the ballast turnout. The static stiffness of the iron plate of the ballastless turnout changes rapidly in the cold, windy, and sandy areas. The gradual stiffness deterioration of the elastic iron plate of high-speed turnout has an effect on the dynamic performances. Under stiffness deterioration, the rail deformations in the turnout zone decrease, the wheel-rail dynamic interactions increase, and the safety parameters increase. The moving trajectories of the vehicle and wheelset are basically unchanged, but the vibration of both the wheelset and vehicle intensifies. Under stiffness deterioration of the elastic iron plate of the high-speed turnout, the increase in operation speed leads to further deterioration of the vehicle-turnout system dynamic performances, and the margins of safety and fatigue further reduce. The stiffness deterioration reduces the adaptability of the high-speed turnout to the speed increase. To expand the scope of raising speed, the stiffness deterioration of the elastic iron plate in the turnout zone should be considered. Some elastic iron plates should be replaced appropriately to ensure the running safety and stability. 2 tabs, 9 figs, 30 refs.