Investigations on formation mechanisms of out-of-round wheel and its influences on the vehicle system

Abstract

The railway wheels are invariably subjected to the uneven wear owing to the wheel/rail interaction, and always tend to be an out-of-round wheel. Such wear on the wheel circumference can be classified into the local defect and the periodic uneven wear. The local defects, including the wheel flat and wheel shell, have been well documented, while the formation mechanisms of wheel polygonalizations, especially for high-order polygonal wear, have not yet been explained clearly. The formation mechanisms of wheel polygonalizations are thus initially reviewed and discussed in this study, and the metal cutting theory is also employed to explain the formation procedure of wheel polygonalization. A coupled vehicle/track dynamic model integrating with the flexibilities of the wheelset, bogie and car body is subsequently formulated to investigate the influences of wheel polygonalization on the dynamic responses of vehicle system, in terms of wheel/rail normal forces, lateral forces and accelerations of wheelset and bogie frame. A maintenance strategy for wheel polygonalization considering the different peak-to-peak amplitudes and the number of harmonic waves is proposed on the basis of limit values of wheel/rail vertical force.