Study on stress states of a wheelset axle due to a defective wheel

High magnitude impact loads caused by a defective wheel may excite various vibration modes of the wheelset, and contribute to adversely increases in the stress states of wheelset axle in high-speed conditions. In this study, the wheelset is treated as a flexible body using the finite element method, then integrated to a multi-body dynamic model of a high-speed train coupled with a flexible track slab model. Through this model the effects of wheel defects considering wheel flats and wheel polygonalizations on the stress states of wheelset axle are evaluated in terms of bending stresses of the wheelset axle. The damage tolerances of the wheelset axle are subsequently predicted using the NASGRO algorithm. The results suggest that the impact forces caused by wheel flats and wheel polygonalizations at the wheel-rail interfaces can result in the resonance vibrations of a wheelset and give rise to severe variations in dynamic stresses of the wheelset axle. The wheel defects-induced stress load cycles considerably contribute to the propagations of the initial crack in the wheelset axle, especially for the wheel polygonalization.