Fracture Mechanism Analysis and Structure Optimization of Metro Vehicles Axle Box Lifting Lugs

Aiming at the abnormal fracture problem of the axle box lifting lugs, the vibration acceleration and dynamic stress tests of the lifting lugs are carried out on the actual running line of the vehicle; analysis of time-domain spectrum and transfer function is carried out and the test results are used to determine the vibration characteristics of whole structure; the structural modal analysis and the fatigue life calculation are carried out, which indicates that the natural frequency of the lifting lug coincides with the frequency range corresponding to the peak value of the axle box transmission rate, and the lifting lug structure is excited by the vibration from the axle box, and resonance occurs at the root portion, resulting in insufficient fatigue life and early fracture. Finally, by optimizing the shape of the overall structure, the fatigue life of the lifting lugs is improved to meet the operational requirements.