Mechanism of Polygonal Wear on Wheels of Electric Multiple Units on Lanzhou-Xinjiang Passenger Dedicated Line

Wheels of the electric multiple units (EMU) running on the Lanzhou-Xinjiang Passenger Dedicated Line have undergone severe polygonal wear because of the harsh environment. This wear increases the contact force between wheels and rails, affects the comfort of passengers, and even endangers train running. To deal with it, the models of the coupled friction and self-excited vibration for a wheelset-track-slab system are established on the basis of the wheel polygonal wear rules obtained by the long-term tracking and the frictional self-excited vibration principles. Then, the cause and development pattern of the wheel polygonal wear are studied by using the complex eigenvalue method. The results show that the frictional self-excited vibration caused by the saturated creep force between wheels and rails can easily result in the 15th−16th order polygonal wear on a straight line. Meanwhile, when the braking system is coupled with the wheelset-track system, at the unstable vibration frequencies of the power wheelset and un-power wheelset, the 23th−24th and 22th−23th order polygonal wear emerges. Finally, the increasing adhesion coefficient between the wheels and rails may account for the fact that the wheel polygonal wear develops faster in winter and spring than in summer.