Flying Car Battery Pack Design Based on Tortoise Carapace Bionic Casing and Metamaterial Sandwich Core

To provide reliable impact protection for a flying car power battery pack under stringent lightweight requirements, especially under takeoff, landing, and drop impact scenarios, a biomimetic metamaterial sandwich enclosure inspired by the hierarchical protective architecture of a tortoise carapace is proposed. The enclosure is composed of an outer shell, an internal sandwich core, and an inner plate, through which load diffusion and deformation buffering can be achieved by multilayer structural coordination. Firstly, three core configurations, including conventional honeycomb, a chiral structure with negative Poisson’s ratio (NPR) characteristics, and an NPR concave structure, are comparatively investigated through high-speed impact finite element simulations. The NPR concave structure is regarded as the preferred core configuration due to its more balanced energy absorption behavior and superior deformation stability. Afterwards, the NPR concave structure is embedded into the full battery pack enclosure, and the protective performances of the proposed battery pack are evaluated under representative flying car operating conditions. Compared with those of the conventional honeycomb, the maximum displacement of the proposed battery pack decreases by 49.31% under the takeoff-and-landing overload condition, and the maximum intrusion decreases by 25.94% under the drop impact condition. The results indicate that the tortoise-carapace-inspired metamaterial sandwich structure effectively enhances the deformation resistance and anti-intrusion capability of a flying car battery pack, thereby providing a feasible structural design approach for battery protection in flying car applications.