Dynamic Derailment Behavior and Anti-Derailment Performance Analysis of High-Speed Electric Multiple Units

Abstract

For high-speed electric multiple units, derailment may lead to severe vehicle instability and safety hazards, making it essential to understand post-derailment dynamic behavior and protective mechanisms. To elucidate the dynamic evolution characteristics and anti-derailment mechanisms of high-speed electric multiple units under derailment conditions, a multibody vehicle–track derailment dynamics model was established for both motor and trailer cars, incorporating nonlinear multi-point contact interactions among wheelsets, gearboxes, traction motors, brake discs, rails, fasteners, and slab tracks. Static geometric clearance verification and dynamic simulations were combined to evaluate the anti-derailment performance of different vehicle configurations and the effectiveness of a carbody–bogie anti-yaw stopper. The results show that underframe components are the first structures to interact with the track after derailment and play a critical role in the evolution of vehicle attitude. Compared with the gearbox and traction motor of a motor car, the brake disc of a trailer car provides more effective lateral restraint and energy dissipation due to its lower installation position and more favorable load-transfer path. The anti-yaw stopper significantly suppresses the relative yaw motion between the carbody and bogie, reducing the peak yaw angle by approximately 30–70% and improving post-derailment stability. Furthermore, a time-sequential and complementary protection mechanism is identified between underframe structures and an anti-yaw stopper. These findings provide guidance for the design and evaluation of derailment protection systems for high-speed vehicles.