Dynamic interaction between straddle monorail bogies and elastic track beams: Shimmy onset, growth, and suppression

This study investigates the shimmy dynamics of straddle-type monorail bogies under elastic coupling with the track beam. A dynamic model is developed incorporating the bogie, rubber tires, and an elastic track beam, capturing nonlinear lateral forces at the wheel–rail interface. Comparative simulations of standalone and bogie–bridge–coupled (BBC) systems reveal that nonlinear lateral sliding forces drive coupled yaw–roll shimmy, with frequency locking at the yaw mode of the bogie. Track beam elasticity shifts system stability boundaries and increases the critical damping required for stability, highlighting the effectiveness of yaw damping enhancement. The absence of preload significantly enlarges limit cycles, degrading dynamic performance. The results provide guidance for suspension tuning and elastic track design in monorail systems.