Abstract:

：A numerical method for calculating the modal frequency of a fully equipped high-speed electric multiple unit(EMU) train with the underframe equipment is proposed, and the method is verified by the finite element analysis and a modal test. The influence of the underframe equipment on the car body transmissibility is studied theoretically, the definition of the nominal car body first vertical bending frequency is given. Based on the numerical calculation, the analysis of vibration transmissibility and the modal experiment, the influence of the suspension parameter of the underframe equipment on the car body modal frequency is researched. Results show that the equipment and the car body will create a coupled vibration system with the equipment of elastic suspension, and new vibrations at a lower frequency and a higher frequency will be generated near the original frequency of the car body first vertical bending mode; the mode shape at the lower frequency is that the car body first vertical bending vibrates in phase with the equipment vertical movement, while the mode shape at the higher frequency is that they vibrate out of phase; with the changing of the suspension stiffness of the equipment, the first vertical bending frequency of the car body displays a frequency-hopping phenomenon.

Key words: experimental modal analysis, frequency- hopping, Green’s functions, underframe equipment, high-speed EMU trains