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The battery-pack system of electric vehicles is prone to collide with low obstacles on the road, causing battery short circuits and even explosions. It poses a great safety threat to passengers and drivers. The honeycomb structure's high energy absorption and lightweight properties have made it a popular choice in the automotive industry. This paper designs different bio-inspired honeycomb structures to a battery-pack system of electric vehicles to improve the crashworthiness performance. The effects of different bio-inspired honeycomb structures on the crashworthiness of a battery-pack system during frontal impact are analyzed based on a nonlinear finite element model. First, the geometric parameters of seven different bio-inspired honeycomb individual units are described. The overall structure of the honeycomb is applied to a battery-pack system. Second, the nonlinear finite element model of a battery-pack system and honeycomb structures are established and verified. Then, collision simulations are conducted. The deformation and the maximum stress of a battery-pack's bottom shell are computed. The energy absorbed by the honeycomb structures during frontal impact are investigated. The results indicate that the proposed bio-inspired honeycomb structure mimicking grass stems improves the safety performance of battery-pack systems most. Finally, a parametric design is carried out on the bio-inspired honeycomb structure. The effects of wall thicknesses and the number of replacement hexagons on the crashworthiness performance are analyzed. The honeycomb structure preforms best when thickness is 1 mm and the number of replacement hexagons is 2 and 4. The optimized bio-inspired honeycomb structure reduces the deformation of the battery-pack' bottom shell by up to 30%, and maximum stress by 10%. • The deformation, maximum stress, and energy absorption are investigated. • The effects of seven bio-inspired honeycomb structures are analyzed. • Parametric design is carried out to further improve the crashworthiness performance. • The deformation of the bottom shell can be reduced by up to 30%. [ABSTRACT FROM AUTHOR]

[Display omitted] • Effect of failure mode on bending behavior of a multi-cellular auxetic and non-auxetic structures. • Among multicellular beams, ReH offers superior bending resistance over a wide deformation range. • A new dimensionless assessment criterion, failure sensitivity, is presented. • The bending performance index of multicellular beam structures with respect to solid section is defined. In recent years, metallic honeycomb structures have been popularly researched due to their significant influence on structural strength and rigidity. In this study, the bending response of multi-cellular beam structures with four (hollow tube (HT), square (Squ), hexagonal (Hex) and octagonal (Octa) and Re-entrant honeycomb (ReH)) cross-sections are numerically investigated. Furthermore, using the nonlinear finite element codes LS-DYNA, a comparative study of the energy absorption characteristics between structures with auxetic and non-auxetic beam cross-sections was carried out. The ReH specimen used in the finite element (FE) validation study was manufactured using the Direct metal laser sintering (DMLS) additive manufacturing method to accommodate the complex geometries. FE method analysis are carried out to systematically investigate the influence of the geometrical configuration and identify the failure mechanism on the bending performance. The results show that in the HT structure, an upper corner fracture occurred because of folding in the contact area of the indenter. For Squ, Hex and Octa beam structures, failure occurs due to localized stress caused by buckling in the cell walls. On the other hand, the cross-sectional area of ReH structure tends to shrink under the bending load. Thus, the influence of the local buckling effect could be minimized despite the high displacements. This situation has ensured that the reduction in the moment of inertia of the cross-section remains limited. Furthermore, the specific energy absorption (SEA) capacity of the ReH beam significantly performed 11.3, 3.76 and 1.77 times better than the multi-cellular beam with Hex, Squ and Octa honeycomb beams, respectively. Accordingly, it was understood that the failure of the re-entrant cross-section under severe deformation was more limited than the others. This study is expected to contribute to evaluating the load-bearing capacity of metallic honeycomb structures, including understanding the failure process. [ABSTRACT FROM AUTHOR]