| Summary: | In order to improve the aerodynamic performance and optimization efficiency while wheel lightweight designing, a multi-objective optimization design method of wheel lightweight based on entropy weighted grey relational analysis (EGRA) was proposed in this article. The aerodynamic analysis finite element model of the assembled wheel was established, and the simulation accuracy was verified by experiments. Study the distribution law of performance parameters such as pressure and turbulent kinetic energy in flow field of the car, analyze the variation law of flow field velocity and turbulent intensity in front and rear wheel cavities of the assembled wheel, and analyze the cloud diagram distribution of temperature and surface convective heat transfer coefficient of the brake disc (<inline-formula> <tex-math notation="LaTeX">$h_{c}$ </tex-math></inline-formula>). Research on the influence of wheels with different disc structures on the aerodynamic drag coefficient of the car (<inline-formula> <tex-math notation="LaTeX">$C_{d}$ </tex-math></inline-formula>) and the <inline-formula> <tex-math notation="LaTeX">$h_{c}$ </tex-math></inline-formula>. Combined with grey relational analysis (GRA) and EGRA, the objective evaluation of the comprehensive aerodynamic performance of wheels with different disc structures was given. With the design of experiments (DOEs), 12 important design variables were screened out by contribution analysis method. Using the approximate model method, combined with the RBF surrogate model, a hybrid method combining EGRA and Non-Dominated Sorting Genetic Algorithm-II (NSGA- II) was proposed to lightweight and multi-objective optimize the assembled wheel. Comparing and analyzing the optimization platform recommending scheme, the technique for ordering preferences by similarity to ideal solution (TOPSIS) method preferring scheme and the EGRA method optimum scheme, it was found that the optimal compromise scheme was obtained by the EGRA method, the reduction of the <inline-formula> <tex-math notation="LaTeX">$C_{d}$ </tex-math></inline-formula> was more obvious, and the improvement rates of performance were also more balanced. After multi-objective optimization, the mass of the assembled wheel was reduced by 10.83%, the <inline-formula> <tex-math notation="LaTeX">$C_{d}$ </tex-math></inline-formula> was reduced by 5.02%, and the average convective heat transfer coefficient of brake disc (<inline-formula> <tex-math notation="LaTeX">$h_{a}$ </tex-math></inline-formula>) was reduced by 8.02%. The optimized assembled wheel has a weight reduction of 32.74% compared with the same type of cast aluminum alloy wheel, which has a remarkable lightweight effect and significant reduction on the <inline-formula> <tex-math notation="LaTeX">$C_{d}$ </tex-math></inline-formula>.
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