Impact resistance optimization design of the NPR sandwich structure for vehicle power battery pack

TIAN Linli; LI Pengju; ZHANG Wenhua

doi:10.16579/j.issn.1001.9669.2026.08.001

Abstract：[Objective]To address the insufficient bottom impact resistance of electric vehicle power battery boxes against road debris,a sandwich structure with negative Poisson ratio(NPR)was proposed to enhance the protective performance of the battery pack bottom while satisfying lightweight design requirements.[Methods]Firstly,a finite element model of the battery pack system under typical ground impact conditions was established using HyperMesh software and Ls-Dyna software,and the compression variation curves of battery cells were obtained to verify the reliability of the simulation model.Secondly,the concave arc NPR structure was adopted as the core layer of the sandwich panel.With the thicknesses of the bottom plate,top plate,and core plate,together with the cell length and concave arc radius,as design variables,and the specific energy absorption and battery axial compression as optimization objectives,multi-objective optimization was conducted based on the optimal Latin hypercube design,Kriging surrogate model,and non-dominated sorting genetic algorithm Ⅱ,so as to establish the mapping relationship between structural parameters and protective performance.Finally,the satisfaction function was employed to select the optimal combination of structural parameters from the Pareto optimal solution set,and the reliability of the optimization results was verified through simulation.[Results]The results show that,compared with the homogeneous aluminum alloy protective plate,the optimized NPR sandwich structure achieves an increase in specific energy absorption from 123.69 J/kg to 141.95 J/kg,representing an improvement of 14.76％;the mass of the protective structure is reduced by 13.38％;and the maximum axial compression of the battery decreases from 3.15 mm to 1.12 mm,with the protective effect parameter reaching 64.44％.The optimization scheme can effectively reduce the risk of thermal runaway of the battery box under impact,and can provide a reference for the impact-resistant structural design of power battery box bottoms.