System dynamics in structural strength and vibration fatigue life assessment of the swing bar for high-speed maglev train

Abstract

High-speed maglev trains are subjected to severe dynamic loads, thus posing a failure hazard. It is necessary to account for the vehicle dynamics to improve the structural strength and fatigue life assessment approach under harsh routes and super high-speed grades. As the most critical load-carrying part between the vehicle body and levitation frames, the swing bar was taken as an example to demonstrate the significance of vehicle dynamics to integrate classical structural strength and fatigue life with the service conditions. A multiphysics-coupled dynamic model of an alpha improvement scheme for an electromagnetic suspension maglev train capable of 600 km/h was established to investigate the complex dynamic loads and fatigue spectra. Using this model, the structural strength and fatigue life of the wrought swing bars were investigated. Results show only a slight effect on the structural strength and fatigue life of swing bars by the super high-speed grades. The nonaxial bending moments caused by the uncompensated relative displacement between the vehicle body and bolsters are identified as the decisive factors. The minimum safety factor of the structural strength for wrought swing bars is 1.33, while the minimum fatigue life is 34 years. Both match the design requirements but are not conservative enough. Therefore, further verification and optimization are recommended to improve the design of swing bars.