## 4 Battery Pack Protection Strategy Development
### Side Pole Impact Performance Analysis of Protection Solutions  
(1) Comparison of Maximum Intrusion of Battery Pack Side Wall  
Figure 12: Cross-sectional design dimensions of our bionic thin-walled structures.  
Figure 13: Finite element model of a side longitudinal beam filled with a bionic lotus root-like thin-walled energy-absorbing structure.  
reduce the maximum side intrusion of the battery pack, by 43.8% and 43.5%, respectively. From a lightweight perspective, the thin-walled energy-absorbing structure (Solution 2) offers a more significant advantage, though its manufacturing process is more complex, and its mechanical properties still need to be further verified.  
Both protective solutions for the battery pack have their unique advantages; however, they differ significantly in terms of implementation feasibility and mass production considerations. On one hand, the thin-walled energy-absorbing structure offers a clear advantage in lightweight design, with the total mass of the side longitudinal beams increasing by only 23.2%--significantly lower than the 63.7% increase observed in the thickened side longitudinal beam solution. From a technical performance perspective, both solutions provide comparable protection for the battery pack, reducing the maximum side intrusion by approximately 43.5% to 43.8%. Nevertheless, when considering engineering feasibility, the two solutions present markedly different challenges.  
Although the thin-walled energy-absorbing structure demonstrates excellent theoretical performance, it faces significant limitations in industrial production. Specifically, these include complex manufacturing processes, high difficulty in mass production, and the need for further research to verify its mechanical properties. In contrast, increasing the side  
Figure 16: Side intrusion curves of the battery pack for each solution.  
Figure 15: Comparison of battery pack deformation in each solution: (**a**) original design solution; (**b**) after optimizing the vehicle body; (**c**) thickened side longitudinal beam; (**d**) after optimization with filled thin-walled energy-absorbing structure.  
longitudinal beam thickness offers several practical advantages: a mature manufacturing process, easier mass production, and relatively controllable technical risks.  
Among these solutions, Solution 2--which involves filling the thin-walled energy-absorbing structure--demonstrates significant potential for widespread adoption due to its balanced approach between technical performance and production feasibility. While further optimization of the manufacturing process is necessary to facilitate large-scale application, the inherent advantages of this solution, such as a mature manufacturing process and controllable technical risks, make it a particularly promising choice for battery pack protection.  
However, it is important to note that manufacturing bionic thin-wall structures presents three key challenges: (1) material-process compatibility for high-strength steel; (2) scalability of precision forming techniques (e.g., laser/hydro-forming); and (3) cost management in mass production. Although advanced hybrid manufacturing shows potential for addressing these challenges, its implementation requires significant tooling investments and process optimization to achieve economic viability. Therefore, while the technical merits of these solutions are clear, their practical implementation must carefully balance performance requirements with manufacturing constraints.