Abstract: To reduce the carbody flexible vibration, the carbody is modeled as an Euler-Bernoulli beam. The optimum suspension frequencies for various equipment are calculated based on the dynamic vibration absorber(DVA) theory. A vertical mathematical model containing flexible carbody and equipment is set up to study the influence of equipment mass, suspension stiffness, damping and mounting position on the carbody vibration reduction. A three-dimensional rigid-flexible coupled vehicle system dynamics model is established to simulate the vibration response of carbody and equipment for the track irregularity. The mathematical analysis shows that the DVA theory can be applied to design the suspension parameters of equipment, and indicates that it’s applicable and effectively to reduce the flexible vibration of carbody which the vertical bending mode is restrained significantly. The heavier the equipment and the closer to the carbody center of mounting position, the greater are the flexible vibration reduction of carbody, and the suspension frequency should be close to the frequency of vertical bending mode. In addition, the damping ratio of suspension elements should remain a certain range from 0.05 to 0.20. The dynamics simulation agrees with the mathematical analysis and shows that the higher the running velocity, the greater is the vibration reduction. The tests for electric multiple units on the roller test rig indicate that the riding comforts can be improved effectively for the elastic suspension of equipment, which shows a good agreement with the former analyzing. The feasibility and effectiveness of DVA applied on flexible vibration reduction of carbody have been verified again.

Key words: electric multiple units;carbody;flexible vibration;dynamic vibration absorbers;suspension parameters