Research on dynamic analysis and maintenance strategy for hard bending of high-speed turnout switch rail

Plastic deformation occurs in the turnout switch rail during loading, unloading, transportation, and storage, resulting in hard bending of the switch rail. The hard bending of the switch rail will lead to an abnormal increase in insufficient displacement, resulting in the geometric size exceeding the limit and the potential risk in the train operation. However, the dynamic simulation of the turnout area has not fully explored the potential impact of the insufficient displacement caused by the hard bending of the switch rail on driving safety. Therefore, this paper establishes a high-speed railway EMU-turnout dynamics model to evaluate the influence of the hard bending of the switch rail on the safety and stability of the train. The results show that the influence of theoretical and measured switch rail hard bending amplitude on the vehicle dynamics index is limited when it is 4 mm or less. However, when the hard bending amplitude of the switch rail increases to 8 mm, the relevant vehicle dynamics indexes increase significantly. The maximum derailment coefficients under the theoretical and measured hard bending of the 8 mm working conditions are 4.42 times and 6.71 times the normal working conditions, respectively. The wheelset lateral force is 4.55 times and 6.86 times the normal working conditions, but they are all within the safety limit. The on-site verification also confirms that there is no significant change in the vertical and lateral acceleration of the car body under the 4 mm hard bending of the switch rail. Finally, a maintenance strategy for the insufficient displacement caused by the hard bending of the switch rail is proposed and the effectiveness of the maintenance strategy is verified in the case study.