Design And Optimization Of 10m Bus Body Based On Rollover Safety

Bus rollover safety is an important research topic for the design of bus body structure.GB17578-2013 has a description as followed: Loaded on each seat equipped with the member restraint device,the loading mass is 50% of each member. The standard was formally implemented July 1, 2015 which leads a more stringent requirement for bus rollover safety. In the past, if the stiffness or strength of the body can’t meet the requirements when designing the body structure, the conventional method is to reinforce the weak parts to meet the requirements. The key factors affecting the rollover safety have not been studied. It will not only have a negative impact on weight reduction but also bring other problems. In this paper, a research for a 10 m bus body is done via the finite element analysis to optimize the body structure. The purpose of this research is to summarize the key factors to bus rollover safety, master the law and the typical structures on bus rollover performance design which will be used in future design.This subject studies on a new 10 m bus for upscale market in East China. The initial solution of the bus body structure is composed of seven closed loops in which there are four completed closed loops and tow double closed loops connected with cowl panel and back panel in Q345. Pillars of closed loops are invaded into the living space by analysis of finite element model which is improved to meet the regulations and ensure the progress of research. Though the structure meets the demands, it is not the optimal solution.The rollover test shows that the closed loop is an important structure on bus rollover safety during optimizing the bus body. A subject will be studied on closed loops to summarize the influence of rollover safety of the body structure. Firstly, the influence of section dimension and material on the rollover performance is studied, in view of the moment rotation and rollover simulation method, and the optimum section dimension and material is achieved for 10 m bus. Then according to the local deformation characteristics of the side wall pillar, two improved schemes are proposed. The simulation results verified the improved effect of two improved schemes, and an optimum scheme is selected on basis of analysis on advantage and disadvantage. Meanwhile, the influence of the integrity and amount of closed loops on the rollover performance is discussed. The simulation results show the completeness of closed loops has little effect on the performance of bus rollover safety depends on the reasonable substructure of side wall pillar, the structure with double closed loops that lies to the body front wall and body rear wall performs better, and the structure with 6 closed loops can meet the regulations of rollover safety for 10 m bus.Finally, the influence law is used to optimize the 10 m bus body which is compared with the previous structure. The optimized structure can not only improve the performance of rollover safety but also meet the performance of ultimate strength. Meanwhile, High strength material is used in optimized body structure which can meet the requirements of more stringent rollover safety regulations.