The Lightweight Research Of Car Frame Based On Frontal Crash

The automobile lightweight design need to take the safety performance intoaccount. The paper puts a designing vehicle as object of study in a project, and findsthe shortcomings in the design of the car according to the collision simulationanalysis, and using the response surface approximation modeling and geneticalgorithm to optimize the automobile frame in order to achieve the purpose oflightweight under the precondition of the safety.Firstly, according to the designing vehicle, a FE model is established, and thefrontal crash simulation results are analyzed. The results show that the energyabsorption effect of front longitudinal beam is poor, causing the peak accelerationvalues of B pillar too high. The actual impact experiment of the front side rail hasvalidated that; the carring capacity of cowl panel is insufficient, which causes largedeformation, this may do harm to the front passengers.Secondly, in view of the shortcomings of the car in the frontal collision, optimizethe main load-carrying parts in the frontal collision. Choose the material thicknessesof the bumper, front longeron, cowl panel, side panel as design variables, the totalquality of the above4parts as the optimization object variable, and B column peakacceleration and the cowl panel invasion peak as constraint to establish theoptimization problem.Finally, use the central composite experimental design method to sample thedesign variables, then get the constraint function values by submit the sample datainto the finite element model. On this basis, the response surface approximationmethod is used to buld the equation of the design variables and the peak accelerationvalues of B pillar and the invasion peak values of the cowl panel.Use the geneticalgorithm to optimize the approximate model of lightweight frame. The optimizationresults show that the total weight of4parts has reduced by30.43kg, lightweight effecthas reached28%, while the peak acceleration values of B pillar and the invasion peakvalues of the cowl panel has decreased. The optimized structure has reached thelightweight and frontal crash safety requirements.This paper which is based on the analysis method of finite element simulation ofautomobile crash and combined the response surface approximation modeling method with genetic algorithm, solves the conflicts between the lightweight and the securityeffectively. And this method can shorten the design time to a certain extent, reduce thedesign cost, and has good engineering significance.