Improving the stability of high-speed trains using an innovative passive yaw damper

Ensuring lateral stability is essential for achieving excellent operation safety and ride comfort of high-speed trains. However, complicated operational environments, particularly various wheel-rail contact geometries, would result in the occurrence of hunting instability. This study presents an innovative passive yaw damper to improve the stability of a high-speed train undergoing extreme wheel-rail contact conicities. A sensitivity analysis of the vehicle stability is first performed to demonstrate the importance of the dynamic stiffness of yaw dampers, promoting the application of the innovative damper. Experimental characterisation procedures enable the detailed investigation into the static and dynamic characteristics of the innovative damper, which are compared with those of conventional passive dampers to highlight the difference. To simulate the dynamic behaviour of the yaw damper, a numerical modelling method based on the Maxwell model is proposed. Using this method, the effectiveness of the innovative damper is assessed in terms of improving the vehicle stability at various wheel-rail conicities. The results show that the innovative yaw damper can ensure carbody stability at low conicity and bogie stability at high conicity, superior to conventional dampers, which fail to balance the vehicle stability at distinct conicities and usually result in hunting instability in specific wheel-rail contact states.