Effect of rubber ageing on underchassis equipment-body coupling vibration in high-speed trains

Thermo-oxidative ageing of rubber significantly influences the performance of rubber products. Therefore, elucidating the evolution of the thermo-oxidative ageing performance of rubber elements used in connecting underchassis equipment and car body in high-speed railway vehicles is crucial for understanding its impact on the coupled vibration between the high-speed train body and underchassis equipment. In this paper, a ternary mathematical model p-T-t between the change in p of the dynamic mechanical properties of the rubber element, ageing temperature T, and ageing time t was established. Based on the p-T-t model of rubber, Finite element models of the car body and underchassis equipment, rigid-flexible coupling dynamic model of the high-speed train, the effects of the external ambient temperature, excitation frequency, and thermo-oxidative ageing on the coupling vibration between the vehicle body and suspended equipment were investigated. The results indicated that ageing rubber aggravated the coupling vibration, and significantly influenced the main frequency peak near the first-order vertical bending frequency. Moreover, as the rubber aged, the vibration energy distribution changed, which is related to the two newly generated vertical bending modes. With an increase in service life, the vertical Sperling smoothness index of the train showed a gradually increasing trend. The research results can provide a theoretical reference for the vibration isolation control of high-speed train rubber elements on the car body and underchassis equipment.