Research on vibration fatigue and failure mechanism of the wire bracket for high-speed train

Abstract

A wire bracket is a cantilever structure connected to the axle box of a high-speed train. Its force is complex and it is prone to vibration fatigue failure. Combined with fracture analysis and on-track tests, the local cracking of the wire bracket is studied and the mechanism and cause of structural failure are revealed. The results show that a fatigue crack in the wire bracket initiates from the incomplete penetration defect of the bolt hole weld of the cantilever side mounting seat and propagates to the upper cover plate and vertical plate. The joint action of wheel polygon and rail corrugation results in higher vibration energy of the wire bracket in 400–800 Hz. The welding defects reduce the fatigue strength of the weld, and the high-frequency and high-amplitude vibration caused by wheel-rail excitation makes the stress concentration near the weld, which brings the possibility of fatigue crack initiation and propagation of the wire bracket during the on-track operation.