The derailment behaviour and mechanism of a subway train under frontal oblique collisions

Abstract

Frontal oblique collision is more likely to cause train derailment and result in more serious consequences. In order to investigate the effect of impact angle on the derailment behaviour and mechanism of a subway train under frontal oblique collisions, a finite element model of train-rigid wall is established based on a four-section train running at 25 km/h. The oblique impact angle ranges from 6.34° to 45°. Numerical results indicate that middle coupler movements and lateral impact force are two main factors influencing derailment behaviours of the train during oblique collisions. For this reason, at 6.34°, the train has no risk of derailment. As the impact angle increases to 11.31°, train derails in saw-tooth mode and rear bogie of vehicle 1 derails. In oblique collisions of 15° and 20°, little-zigzag mode occurs with vehicle 1 and front bogie of vehicle 2 completely dropping from rail. However, once impact angle exceeds 25°, different movements of middle couplers have little influence on train derailment behaviours because impact force plays a leading role. In this condition, only vehicle 1 derails and the rest vehicles are not affected. Train derails in large displacement lateral mode. As to the analysis above, limiting yawing movement of middle couplers and improving lateral crashworthiness of vehicle structures are effective measures to decrease the risk of train derailment during oblique collisions.