A magneto rheological hybrid damper for railway vehicles suspensions

High speed railway vehicles features a specific lateral oscillation resulting from the coupled lateral displacement and yaw of the wheelset which leads to a sinusoid movement of the wheelset along the track, transferred to the entire vehicle.The amplitude of this oscillation is strongly dependant on vehicle's velocity.Over a certain value, namely the critical speed, the instability phenomenon so-called hunting occurs.To raise the vehicle's critical speed different designs of the suspension all leading to a much stiffer vehicle can be envisaged.Different simulations prove that a stiffer central suspension will decrease the passenger's comfort in terms of lateral accelerations of the carboy.The authors propose a semi-active magneto rheological suspension to improve the vehicle's comfort at high speeds.The suspension has as executive elements hybrid magneto rheological dampers operating under sequential control strategy type balance logic.Using an original mathematical model for the lateral dynamics of the vehicle the responses of the system with passive and semi-active suspensions are simulated.It is shown that the semi-active suspension can improve the vehicle performances.