Study on Wheel Polygonal Wear of Metro Trains Caused by Frictional Self-Excited Oscillation

Abstract

This article aims to study the special phenomenon of wheel wear occurring on trains operating on a metro line in which the wheel polygonal wear rate of the right wheel is higher than that of the left wheel. Based on the perspective that frictional self-excited oscillation causes wheel polygonal wear, a flexible wheelset–rails system was built and, using complex feature value analysis, the unstable vibrations of this system were investigated. Moreover, the factors influencing wheel polygonal wear were studied. The simulation results show that when a subway train runs on a tightly curved track at 50 km/h, saturated creep forces upon two wheels of the leading wheelset are created. These forces can lead to unstable vibrations at frequencies of about 51, 60, and 69 Hz that are capable of inducing ninth-order wheel polygonal wear. Based on modal analysis and transient analysis, it is found that the unstable vibration intensity of the inner wheel–rail system is greater than that of the outer wheel–rail system, which leads to more uneven wear on the inner wheel. The length difference between the right and left curved tracks is the main reason for the different polygonal wear rates between the right and left wheels. The addition of damping material to the surface in the middle part of the wheelset axle has a small effect on the inhibition of wheel corrugation caused by the unstable vibrations. Fastener failure can lead to a stronger tendency toward wheel polygonal wear.