Abstract: The stability of the high-speed train(HST) with semi-active suspension is studied comprehensive using the nonlinear bifurcation theory. The high-speed train model, semi-active damper model and the semi-active controller model are set up. Using those models, the co-simulation model system of the semi-active high-speed train is built. The nonlinearities of the wheel/rail contact and the yaw damper are analyzed. The hunting bifurcation graph of the high-speed train with the semi-active is calculated using the brute-force method. The influence of the semi-active suspension on the stability of the HST which equipped the damping type yaw damper and the high conicity thread is less. It reduces the critical speed of the HST about 15 km/h, which equipped the friction type yaw damper and the high conicity thread. However, if the HST equipped the friction type yaw damper and the worn low conicity tread, the semi-active suspension would worsen dramatically the stability. The semi-active suspension should be chosen carefully as designing the HST suspension system, when the low conicity thread and friction type yaw damper have been adopted. The influence of the wear of tread on the stability semi-active suspension HST should be concerned in the process of service.

Key words: bifurcation, high-speed train, semi-active, stability