The mechanism of wheel polygonal wear based on rotor dynamics

A rotor dynamic model of wheel-rail coupling system was established taking wheel eccentricity and initial polygon into consideration in order to investigate the mechanism of wheel polygonal wear. Considering the complex wheel-rail contact relationship, the equivalent yaw angle was proposed and the wheel-rail relative speed model was established. The law of wheel-rail self-excited vibration and its effect on polygonal wear were studied. The possibility of variable speed operation was investigated together with the sensitivity of the system parameters. The results show that the periodic longitudinal and lateral creep forces are essential for the wheel polygonal wear, which have the characteristics of supercritical Hopf bifurcation and 'fixed wavelength' and 'fixed frequency'. While in some circumstances, longitudinal and lateral creep forces jointly cause polygonal wear, in other cases, longitudinal creep forces have almost no effect. By adjusting the longitudinal and lateral stiffness, primary suspension stiffness, and rail damping parameters, as well as by selecting an appropriate speed for variable speed operation, the wheel polygonal wear may be effectively suppressed. The findings offer a fresh viewpoint for the study of mechanisms and the prevention of wheel polygonal wear.