Research Of Multi-objective Optimization For The Thickness Of Vehicle Door Structure Parts Based On Stiffness And Modal

In vehicle body design, the vehicle door is an important and independent part which should has excellent performance in stiffness and vibration. However, light-weight design of vehicle door is the serious means to improve fuel economy. Therefore, it's an intersting challenge to both satisfy these perfermances mentioned above and reduce the weight of the vehicle door. Hence, multi-objective optimization is helpful to vechicle door design.A multi-objective optimization method is proposed to vehicle door desgin by considering multi-working-conditions which includes vertical stiffness and first-order modal. And the optimum parameters of thickness for door parts are found to reduce the total weight. The main works are as follows:(1) The finite element models about vertical stiffness and free modal are established respectively, and their initial design values are calculated. According to the finite element model, the thickness sensitivity for the door parts are analyzed to choose reasonable parts as optimization objects.(2) Latin square experimental design method is applied to sample the vertical stiffness and the first-order mode with different values, then the second order response surface model is used to build the relationship between design variable and outputs which includes vertical stiffness and first-order mode. Additionally, this model is confirmed by precision testing that it can replace the finite element models to implement multi-objective optimal design. Based on these researches, the multi-objective optimal model of the vehicle door is constructed under the multi-working-conditions.(3) The optimization models are further interfaced with multi-objective genetic algorithm to obtain the non-Pareto optimal solution set from which the final optimal results can be choosen according to practical design principle. The results shows that the design requirements in vertical stiffness and the first-order mode are commanded and the weight are also decreased. Finally, the optimization results are verified by the finite element method that the optimization method is reliable and effective.