Analysis of the effects of vibration modes on fatigue damage in high-speed train bogie frames

High-speed trains have been rapidly developing in China, and their operating speeds have reached 350 km/h. In order to ensure the structural reliability and safety of high-speed trains, dynamic design methods need to be adopted to extend the fatigue life and maintenance period. This paper presents a detailed study of the effect of vibration modes on fatigue damage in a highspeed train bogie frame under random loading conditions, which considered the expansion of the excitation frequency range and the proportional increase of the high-frequency components. Firstly, a detailed finite element model of the bogie frame was established using a commercially available finite element software and the constrained modes were analyzed by using the Block Lanczos mode analysis procedure. The modal results were compared and verified by test modal results, which were consistent in the two modal results. Next, a full-scale rigid-flexible coupling vehicle dynamics model was established for obtaining the load-time histories of the bogie frame force bearing positions, which compared the vibration responses in the time and frequency domain. Then, based on the dynamic design methodology and the random load spectrum of the bogie frame, the modal superposition method coupled with the Miner's rule and the material P-S-N curve were applied to analyze the effect of vibration modes on fatigue damage of the vehicle bogie frame. Finally, the maximum fatigue damage and damage of hot spot locations affected by the modes were discussed. The results show that the modes of the bogie frame, especially certain low-order such as modes 2, 5, 6 and 8, contributed significantly to the vibration response and fatigue damage. The results of the analysis consistently match the actual failure locations of the bogie frame from past experience. The modal superposition method based on the dynamic design methodology is a very effective method to study the fatigue strength problems due to vibration, and the fatigue reliability of the bogie frame can be increased by improving the dynamic performance of the bogie frame according to the results of the analysis.