Optimisation of secondary suspension dampers to improve the ride comfort of high-speed rail vehicles

Optimal design of the secondary suspension of high speed rail vehicles should not only provide proper damping of the rigid carbody modes, but should also limit force transmission at higher frequencies, so as to reduce as much as possible the excitation of flexible modes. This paper investigates the possibility of tuning the characteristics of traditional passive dampers, so as to meet the above requirements. Reference is made to a meaningful case study, which is supported by comprehensive experimental data coming from both experimental modal analysis and on-track tests. Laboratory tests on different kind of secondary suspension dampers were performed, so as to simulate the real working conditions and to optimize their dynamic stiffness. As a result of the collected data, the damper properties were tuned in terms of both force-velocity characteristic and bushing stiffness, so as to reach the optimal behaviour in terms of vehicle comfort.