As a core safety component of new energy vehicles, aluminum alloy battery housing requires a multi-dimensional collaborative design approach, encompassing material selection, structural topology, connection processes, and energy absorption mechanisms, to optimize its impact resistance. While aluminum alloys inherently possess advantages in lightweight and high specific strength, their dynamic mechanical properties need further enhancement through alloying and heat treatment processes. Simultaneously, T6 heat treatment achieves precipitation strengthening, refining grains and increasing dislocation motion resistance, thereby enhancing the material's resistance to deformation under high-speed impacts.
Structural topology optimization is a key method for improving impact resistance. Finite element analysis (FEA) simulations of collision scenarios can identify stress concentration areas and optimize load transfer paths. For example, stiffened structures are employed in battery housing frame design, with longitudinal and transverse stiffeners placed in critical areas to form a multi-cavity structure that disperses impact energy. The stiffening layout must adhere to the principle of equal stiffness, ensuring balanced stiffness in all directions and avoiding localized overload. Furthermore, iterative design of the shape and distribution of stiffeners using topology optimization algorithms can achieve lightweighting while maintaining structural strength. For instance, the optimal stiffening dimensions obtained through genetic algorithm optimization can significantly improve energy absorption efficiency.
The impact of the joining process on the overall impact resistance cannot be ignored. Aluminum alloy battery housing typically uses friction stir welding (FSW) to join components. This process uses frictional heat to bring the material to a plastic state, forming a solid connection under pressure, avoiding the porosity and cracking defects of fusion welding. The mechanical properties of FSW welds are close to those of the base material, and the residual stress is low, effectively preventing structural failure caused by weld cracking during impact. For complex structures, a combination of die casting and welding can be used. Small components are integrally formed by die casting to reduce connection points, while large components are expanded in size through profile welding. Simultaneously, local reinforcement design can compensate for the performance degradation in the heat-affected zone of welding.
The design of the energy absorption mechanism must consider both active protection and passive buffering. A gradient buffer structure can be set in the outer layer of the battery housing, for example, using foamed aluminum or honeycomb aluminum composite materials of different densities. The high-density outer layer absorbs the initial impact energy, while the low-density inner layer further decelerates and disperses the remaining energy. Deformation space must be reserved between the buffer layer and the aluminum alloy frame to avoid secondary damage caused by rigid contact. Furthermore, isolation devices can be installed between battery modules. For example, separators made of ductile materials such as polypropylene (PP) have a much higher fracture strain value than aluminum alloys, allowing them to absorb energy through plastic deformation during impact and prevent short circuits.
Surface treatment processes can significantly improve the impact and wear resistance of aluminum alloy battery housings. Hard anodizing increases surface hardness to 400-600 HV by forming a dense oxide film, while also improving wear and corrosion resistance. For high-risk areas, spraying techniques can be used to deposit ceramic particles or silicon carbide (SiC) coatings, forming a composite surface layer with a hardness exceeding 1000 HV, effectively resisting scratches from sharp objects. Electroplating can improve surface toughness by depositing a nickel-based alloy layer, preventing brittle spalling caused by impact.
Multi-material synergistic design is an important direction for future optimization of impact resistance. For example, embedding carbon fiber reinforced polymer (CFRP) reinforcements within an aluminum alloy frame leverages CFRP's high specific strength and modulus to enhance impact resistance in critical areas. Simultaneously, effective load transfer is achieved through interface design between the aluminum alloy and CFRP. Furthermore, the application of smart materials, such as shape memory alloys (SMA), allows for the automatic recovery of some deformation after impact, providing adaptive protection for battery housing.
Optimizing the impact resistance of aluminum alloy battery housing requires a collaborative design across the entire chain, encompassing materials, structure, process, and energy absorption. From the selection and heat treatment of high-strength aluminum alloys to topology-optimized reinforced structural layouts; from high-quality connections achieved through friction stir welding to the energy absorption mechanism of gradient buffer layers; and further to surface strengthening and multi-material collaborative design, meticulous control at each stage can significantly improve the safety performance of battery housing under complex impact scenarios, providing a solid guarantee for the reliability of new energy vehicles.
