Fatigue Analysis of Bogie Frame under Wheel-Rail Impact Load

doi:10.19301/j.cnki.zncs.2025.11.009

Abstract：Metro vehicles are prone to bogie frame fatigue damage due to wheel-rail impact loads during operation, which threatens operational safety. Based on SIMPACK software, the flexible body files of the bogie frame and track were generated through the FEMBS interface, and a vehicle-track rigid-flexible coupled dynamic model was established by combining the Flextrack module. The saddle-shaped welded joint was used as the impact load input for dynamic simulation, finite element modal analysis, and fatigue assessment. The equivalent stress amplitude was calculated using the rainflow counting and S-N curve methods, and the fatigue strength was evaluated according to the FKM standard. The results show that when the vehicle passes through the welded joint, the wheel-rail force and axle box acceleration fluctuate significantly. The P2 force (approximately 52 Hz) excited by the wheel-rail impact is transmitted upward to the bogie frame, inducing mode resonance at 46.3 Hz and 55.5 Hz, leading to fatigue damage in critical areas such as the motor hanger welds. Reducing the operating speed (to below 50 km/h) can reduce the amplitude of the wheel-rail force; reducing the primary suspension damping can improve vibration isolation performance and suppress the transmission of the P2 force; reducing the unsprung mass can both lower the amplitude of the wheel-rail force and increase the P2 resonance frequency to avoid mode resonance, thereby effectively alleviating the bogie frame damage. The research results provide references for the fatigue protection and intelligent maintenance of metro bogies.