Vibration analysis of a Wheelset–Bogie system under periodic wheel out-of-roundness excitation

Based on measured data of wheel polygonisation, multiple excitation models are established to analyze the differences in vibration response between wheelsets and bogie frame under the excitation of wheel polygonised wheels and wheels with flats. The superposition method and phase change relationship of defect excitation on coaxial axis have been innovatively proposed, and the interaction mechanism of defect excitation and its influence on the vibration characteristics of system have been deeply explored. The conclusion is as follows: (1) There is a significant coupling effect between the amplitude of the wheel polygon and the speed, and the vibration of the bogie frame is mainly affected by high-order polygon excitation, which are mainly concentrated in the 18th to 27th orders. Compared to speed, the damage caused by the length of the wheel flat is more pronounced, and the wheel flat enhances the vibration intensity of the frame. (2) At low speeds, wheel flats have sufficient wheel-rail contact and are prone to resonance with adjacent structures. However, at high speeds, inertia causes a shorter wheel-rail contact time, and the flat effect is not effectively utilized. At this time, the influence of polygonal wheels on vibration frequency is higher than that of wheel flats. (3) The wheel polygonal excitation with continuous periodic characteristics is the dominant factor in the frame vibration, and the peak frequency gradually increases with the increase of speed. The effect of wheel flat excitation on frame vibration depends on the speed, and it only has an enhancing effect at low speeds. The study has revealed various response characteristics of wheel defect coupling excitation, providing theoretical basis for vehicle operation safety and defect identification.