The Numerical Simulation Of Light Rail Vehicle Dynamics

With the extensions of city scopes and the changes of city developing modes, the public transport not only requires large quantity but high quality. To ameliorate the public traffic problems, the perfect urban rail transport systems have been developed in many developed countries, besides the traditional road traffic, which have formed a solid urban rapid rail traffic netvvork include ground, underground and over-ground. As an effective traffic of light rail transit, it has been widely adopted by many large cities over the \vorld, and a few cities of China are planning or building the light rail transit in our country, which has characteristic of saving investment, short construction period, high flexibility and low life-cycle costs for the light rail transit which can be constructed underground or high frame in crucial area, which can be suitable for the requirements of large capacity, high speed, safety and punctuality. Demands for greater comfort standards and ease access for the disabled are developing the lo\v floor light rail vehicles(LRVs). The new generation of low floor LRVs involve many new technologies include modular bodies, independently rotating wheel(IRW) bogie, AC transmission and low floor vehicles etc.There must be many differences in the bogies between conventional vehicles and the low floor LRVs. First, traditional vvheelset, vvhich includes a axle and two wheels is not suitable. As a method of reform, the independently rotating wheels are introduced, which abandon the axle or fixes the stepped axles in order to keep the spare space between two wheels. For driven-bogie, the installation of the traction motor is one of the important technologies. Second, the dynamic behavior of negotiating the curves may be \vorsened, so different linkage bars should be adopted.In order to simulate the dynamic behavior of LRVs, it need rebuild the vehicle simulation model because of the structure's changing. In this paper, the author starts with seeking the difference betvveen traditional vehicles and LRVs, the lateral simulated model of single independently wheelset is built, and enlarge it to lateral simulated model of the whole LRV. The dynamic performances of thelateral response, lateral stability on the tangent track and dynamic negotiating curves of LRV with IRWs are discussed in detail, also comparing dynamic behaviors with conventional passenger cars. When analyzing the lateral response and dynamic negotiating curves, 25-Digree Of Freedom(DOF) is introduced, while 21-DOF in lateral stability analyzing. The reason is that the critical speed should be theoretically infinite for LRV with independently rotating wheel which is difficult to 鎍kulate, and from another point, starts with the lateral stability of Elasto-Damper Coupling wheelet (EDCW) which could be identical with IRWs when assume corresponding parameters. In this method, the DOF is 21.In the processing of the numerical simulation of LRV dynamics, Knowing from the creepages of IRW first, wheel profile has sensitive effect on IRW creepages, so the wheel profile should be selected cautiously to optimal the vehicle dynamic behaviors. Next, the longitudinally creep force is disappeared, so the self-oscillation vvill don't occur and the bogie is stability. While the natural steering action of \vheelset is lost which means that some sort of steering action is necessary to keep the wheelset appropriately aligned on a curve. It is referred two way to resolve this problem include pure mechanism and active guided in this paper. Additional, by comparing with conventional bogie, it is discovered smaller lateral body acceleration, but sticks to one rail trends and high vvorn values because of guided by vvheel flange. It should be referred that these results are only useful to special simulation model of LRV with IRWs in this paper.The conflict between hunting stability and negotiating curves, both the LRVs with IRWs and conventional, is notable. In order to obtain the best compromise between stability and curving, there have been proceeding...