Primary Resonances and Secondary Resonances of High-Speed Railway Vehicles Subjected to Unsteady Aerodynamic Loads

Abstract This paper investigates the primary resonance, superharmonic resonance, and subharmonic resonance responses of high-speed railway vehicle systems (HRVS) under the combined effects of self-excitation and forced excitation induced by unsteady aerodynamic loads. First, the problems are solved by numerical method, and the wheelset lateral displacement diagrams, phase portraits, and spectrum diagrams for different resonance situations are obtained. Identification of self-excited vibration components is achieved using the vector diagram and normalized vibration form. The results show that when the excitation frequency of the aerodynamic load falls into some specific frequency bands, in which the values are near-commensurable with the self-excited frequency of HRVS under steady aerodynamic loads, the resonances are excited. In these situations, the system will no longer perform quasi-periodic motions as in nonresonance but will perform periodic motions instead. Furthermore, analytical solutions are derived using the method of multiple scales for nonresonance and resonance situations in different frequency bands of wheelset systems under unsteady aerodynamic load. The amplitude–frequency curves of the primary resonance responses are obtained. The stability of each branch is analyzed, and the variation of the responses with parameters is given. The paper also explains the reason for the mutual transition between the periodic solution and the quasi-periodic solution due to the minor variation of the parameter, and the pull-out frequency and pull-out amplitude are given.