Crashworthiness behavior of multi-cell structures reinforced with small tubes under axial and inclined loading

In this paper, a novel design for the cross-sectional shapes of square, hexagonal, octagonal, and decagonal structures has been proposed for the development of energy-absorbing devices. The deformation behavior of these structures, which contain multiple small tubes, was analyzed under axial and inclined loads (0°, 10°, 20°, and 30°) using a validated finite element model in LS-DYNA, supported by experimental and analytical data. Various crushing metrics such as specific energy absorption (SEA), peak crushing force (PCF), mean crushing force (MCF), crush force efficiency (CFE), and undulation of load-carrying capacity (ULC) were evaluated for the structures. The results indicated an optimal size for the small tubes that maximizes energy absorption capability. Through the TOPSIS method considering 12 criteria, the multi-cell octagonal structure O5, which includes the highest number of small tubes, was identified as the most effective energy absorber. It demonstrated significantly higher Specific Energy Absorption (SEA) values compared to simpler structures S1, H1, O1, and D1, with improvements of 89%, 65%, 53%, and 46%, respectively. Therefore, it could be utilized in automotive structures for crashworthiness applications.