A SMART PASSIVE YAW DAMPER FOR THE REDUCTION OF LATERAL CONTACT FORCES IN LOW-RADIUS CURVED TRACKS

High-speed trains are equipped with yaw dampers to prevent the arising of hunting motion. These suspension components play an important role in improving the vehicle stability. However, the presence of yaw dampers increases the steering resistance of the bogies, especially in transient curve track segments. For this reason, passive yaw dampers are designed according to a tradeoff between improvement of high-speed stability and limitation of curving performance degradation. This paper introduces an innovative passive smart yaw damper, the Position Dependent Yaw Damper, able to overcome the typical limitations of standard passive components. The damper can variate its dynamic performances according to the operating conditions of the vehicle. In this paper, a PDYD prototype will be experimentally characterized. Then, a numerical model of the damper will be tuned on the experimental data. The model aims at predicting the influence of the PDYD on the dynamic performances of a rail vehicle, simulated with a Multibody model. A sensitivity analysis will assess the relationship between different PDYD layouts and the vehicle curving performances co-simulating damper and vehicle models. The numerical comparison will be focused on the low-speed negotiation of low radius curves. Finally, the best PDYD layout will be implemented in a numerical simulation of a high-speed high-radius curve to verify its effectiveness in reducing the arising of hunting unstable motion.