Basic Research Of High-speed Rail Vehicle Carbody Vibration

For the high-Speed Railway applications, the carbody vibration of High-Speed Rolling Stocks (HSRS) is one of the important problems which concern both the ride comfort of HSRS and the vibration fatigue safety of carbody structures. Despite the influential mechanism of lateral ride comfort is very complicated, but in the view point of vertical excitation transmissions of wheel-rail contacts, the excitation of the rail spectrum and the airspring suspension feature are the important influential factors to vertical ride comfort and carbody vibrations. For the distinct effects produced by HSRS with Japanese style airspring or German style airspring:The bogie CRH2C with Japanese style airspring, therefore must be a floating flooring way to isolate the body floor vibration;on the contrary CRH3C with German style airspring, the flooring is still traditional splicing way. The comparative analysis of the German style airspring advantage performance in applications was firstly carried out, further study the necessity of the extra vertical dampers added in secondary suspensions in CRH380B bogies.CRH3high-speed EMU(Electrical Multiple Units) for the study of this paper, follows several studies on carbody vibration of HSRS was done. Firstly, According to the parameters of bellows type airsprings adopted in CRH3/380B bogie, the simplified model of double-oscillators is established, in which the bogie frame and half of carbody is taken as the sprung masses. Orifice diameter as a variable, the contrastive analysis was carried out on suspension features of both German and Japanese style airsprings, shows German style airspring has an advantage in the applications. Secondly, based on the ride comfort evaluation contrasts with the data measured from the acceptance tests of the long train CRH380BL-12, the contrastive study was done on the influences of the four airspring suspension modes to vertical ride comfort. By contraries, the soft-suspensions of German airsprings are still remained under the high-speed running, the vertical ride comfort is therefore evaluated best. Lastly, to analyze the influences of different airspring suspension modes to the floor vibration of carbody, the rigid-flex coupling model of HSRS was established based on the flexible carbody, then the rigid-flexible coupling simulation and floor vibration analysis were carried out. Because negative impact on the elastic vibration of the carbody may by suspension impedance under the high-speed operation, the extra vertical dampers are advised to be cancelled in CRH380B.By modeling, simulation and experimental comparison, reached the following conclusions:because of the different design styles on the orifice’s damping effective between the German and Japanese airsprings, the German airspring suspension remains therefore the ’soft suspension’ under the high-speed operation, but the dynamical stiffness of the Japanese airspring suspension becomes harder remarkably, by which the vertical ride comfort of carbody is affected badly. When the vehicle velocity is raised above300km/h, the vibration of1st vertical floor bending mode begins to be appeared on the end parts of carbody, and increased gradually to the extent that the mode vibration of the local floor above bogie is brought into. For the German airspring suspension, when the secondary vertical damper is added, the unfavorable influence is produced to the carbody end floor vibration. And for the mid floor vibration, there is less relevance to the airspring suspensions.