Analysis of the generation mechanism and evolution of the wheel high-order polygonal wear of subway trains

The present paper aims to study the generation cause of initial high-order polygonization of subway wheels as well as its progression pattern. In analyzing the wear characteristics of out-of-round (OOR) wheels of metro trains obtained via field measurements, the distribution of wheel high-order OOR wear was found to be closely related to the small-radius (i.e., a radius no greater than 400 m) curve track. The friction-induced self-excited oscillation caused by the saturated wheel-rail creep force was used as the frequency-fixing mechanism of the wheel OOR wear, and the wheel polygonization induced via this oscillation was evaluated by finite element simulation. Furthermore, the influence of rail corrugation on the development of wheel OOR wear was analyzed, and it is found that, when the vehicle negotiates a small-radius curve track, an unstable oscillation of 87 Hz induced by the saturated creep force can lead to wheel 12th ∼ 13th-order OOR wear—mainly distributed along the inner wheel tread far from the wheel back. During vehicle operation, the vibrations caused by the wheel 12th ∼ 13th-order polygonization can excite the eigenmodes of the wheelset, leading to an increased wear intensity. In addition, wheel 12th-order polygonal wear interacts with the rail corrugation of the same wear wavelength but different phases, which can cause wheel 10th ∼ 11th- and 13th ∼ 17th-order polygonization.