Research On The Rollover Crash Safety Characteristic And The Key Structure Optimization Design Of Minivan

With the development of social economy and automobile industry,the automobile ownership is growing rapidly.The sales of minivan are rising year by year,for this automobile adapts to the needs of Chinese consumers.Vehicle rollover accident has the characteristics of low incidence and high death rate,which caused it to become the main prevention and control traffic accident type by ministry of public security.In particular,minivan rollover accident has caused the great attention of the state council.At present,there not yet has vehicle dynamic rollover mandatory regulations in the world,so the research of this field is also less or even blank at home and abroad.Therefore,whether in terms of society long-term and stable development and the formation of relevant national laws and regulation,or from the perspective of rollover technology research reserves and auto enterprise development,the research on the rollover characteristic of the vehicles(especially minivan)has great significance.Based on the project work contents of<Study of Safety Technology and Standard for Chinese Mini Van>,the test method,simulation theory and optimization algorithms of the minivan are explored in this paper.Through the method of combining real vehicle physics test to finite element simulation analysis,the improvement of experiment method,the debugging and modification of simulation model,the results comparison of test and simulation,and the promotion of simulation efficiency are researched and analyzed.With the help of computer aided technology,the multi-objective optimization design of the key structure is completed,considering the vehicle rollover crashworthiness,energy absorption and lightweight characteristics in the process.In view of the minivan rollover crash safety characteristic,the main research contents in this paper are as follows:(a)Exploration for basic theory and method of vehicle rollover crashBasing on the FMVSS 208 laws and regulations,improvement scheme of dolly rollover test procedure is put forward,and the mass deployment step before the test are improved,what's more,the test contents of body deformation intrusion and key structure motion parameters are added.The basic theory of dynamic nonlinear andlarge deformation finite element analysis method which applies to the simulation analysis of rollover crash is outlined,such as mechanics equation,integral algorithm and contact algorithm.The application method of computer-aided technology in engineering optimization problems is explored,and the design of experiment,approximation models and multi-objective optimization theories are summarized.(b)Research on physical test and simulation analysis of minivan rollover crashPhysical test procedures and finite element simulation analysis processes of minivan dolly rollover test are introduced in detail.In front of the vehicle test,subsystem test is completed,including tire and wheel assembly,suspension system and top structure.What's more,the debugging and modification for the finite element model is completed after the test.Several aspects are comparative analyzed after the test and simulation of the vehicle dolly rollover,such as calculation reliability,moving posture,motion parameters,components deformation and failure.At the time of target vehicle rollover crash safety characteristic is researched,the reliability,accuracy and precision of the finite element model is validated.To solve the problems of vehicle rollover simulation calculation time is long,"Flexible body-rigid body transformation","motion parameters given" and "comprehensive promotion" efficiency improvement scheme are put forward,and simulation efficiency improvement method used in optimization design stage is determined.(c)Optimization design for key structure with the goal of rollover characteristic improvementAccording to the deformation,stress and energy absorption after the test and simulation,the top 1 # beams,2 # beam,left and right inner panel of A pillar are identified as the key structure in the process of the vehicle rollover crashes.Considering the body structure resistance and energy absorption characteristics,vehicle rollover characteristic evaluation index is researched.According to the engineering optimization design process,the key structure optimization design is completed by the using of Opt LKD experiment design,KRG approximation model building,NAGA-? multi-objective optimization and scale coefficient.It shows that the optimization result is reasonable and the optimization effect is remarkable.