## 5 Conclusions  
This study introduces an innovative approach that integrates ANN, NSGA-II, and TOPSIS methods to optimize the structural design of battery side profiles for electric vehicles. This approach effectively balances the conflicting objectives of minimizing weight, maximizing crash performance, and ensuring safety. This study demonstrated that a hybrid model combining honeycomb and auxetic structures achieved superior crashworthiness and lightweight performance. In conclusion, this study's methodology offers a comprehensive solution not only for optimizing electric vehicle battery carriers but also for addressing similar multi-objective optimization challenges in engineering design. The use of ANN and NSGA-II in combination with decision-making tools such as TOPSIS proved effective in deriving balanced, high-performance design solutions that align with evolving needs in the automotive sector for safety, energy efficiency, and sustainability. \begin{table}
\begin{tabular}{l l l} \hline \hline  & **Current Design** & **Optimized Design** \\ \hline Material & Al 6082-T6 & GFRP-GFR00 \\ Technology & EXTRUSION & PULTRUSION \\ Density (g/cm\({}^{3}\)) & 2.7 & 2 \\ Weight (g) & 7639.65 & 5812.27 \\ Pick force (N) & 56,427 & 49,909 \\ Absorbed energy (J) & 840 & 658 \\ Specific energy absorption (SAE) (J/g) & 0.10995 & 0.11321 \\ Piece cost coefficient & 1.628 & 1 \\ Performance–cost ratio (SAE/piece cost) & 0.06754 & 0.11321 \\ \hline \hline \end{tabular}
\end{table} 
Table 7: Comparison of current design and optimized design. The proposed approach effectively addresses complex design challenges. The results of this study highlight several key findings:  
* Innovative approach: the hybrid optimization methodology successfully combines ANN, NSGA-II, and TOPSIS, providing an effective strategy for balancing conflicting objectives such as weight reduction, crashworthiness, and overall safety. * Optimization of conflicting objectives: The optimization effectively handles multiple conflicting objectives. The primary goals of this study focused on minimizing weight while maximizing crash performance, which is a key consideration in the automotive sector. * Superior hybrid model: the optimized hybrid structure, which integrated honeycomb and auxetic elements, achieved significant improvements in crashworthiness and weight reduction, demonstrating the effectiveness of combining different configurations for enhanced performance. * Weight reduction achievements: Compared with the current design, the optimization achieved a weight reduction of 1.8 kg per profile, corresponding to a 23.9% decrease in weight and a 38.6% cost reduction compared to the original design. These improvements highlight the approach's efficiency and cost-effectiveness, with 3% higher performance. * Performance validation: the optimized design resulted in a peak force of 45,909 N and an absorbed energy of 658 J, with a verification accuracy of 97%, demonstrating the reliability and robustness of the proposed methodology. * Material efficiency: this study emphasized the benefits of using GFRP-GF800 material over traditional aluminum, particularly in terms of weight reduction and energy efficiency, which are critical factors for electric vehicle applications. * Versatility of the methodology: the methodology presented offers a versatile solution not only for optimizing electric vehicle battery carriers but also for addressing similar multi-objective optimization problems in engineering design. * Implications for the automotive sector: this research aligns with the automotive industry's evolving needs for enhanced safety, energy efficiency, and sustainability, providing valuable insights for future structural optimizations in electric vehicles and other applications. All these achievements obtained as a result of this study demonstrate that the approach developed is suitable for industrial applications and serves as a guide for future studies.