Effect of the secondary suspension and intercar links on the performance of a high-speed train

Multibody simulations are a useful tool for studying railway dynamics in different conditions, as they eliminate the need for expensive tests using actual rolling stock. This paper presents a multibody model of an articulated high-speed train with shared bogies, comprising eight passenger cars and nine bogies, that is implemented in Universal Mechanism. The train's critical speed under nominal conditions is determined by the presence of limit cycles in the wheelsets' phase plane of lateral motion and by the standard deviation of their lateral displacement. A sensitivity study is then performed to examine the impact of secondary suspension stiffness and intercar link damping on lateral stability at speeds between 250 km/h and 450 km/h. The horizontal stiffness of the secondary suspension significantly affects the critical speed, making the central cars of the train more prone to oscillations. Conversely, the vertical stiffness of air springs and the damping of intercar dampers have a minimal effect on the train's critical speed. The proposed model is a first step in developing the digital twin of a high-speed train.