Energy Absorption Characterization of Tubes Filled with Auxetic and Non-Auxetic Lattice Structures Under Lateral Loading

This study examines the energy absorption performance of aluminium crash tubes under lateral compression, focusing on the effect of internal lattice fillers. Tubes were tested in both empty and filled configurations, with three distinct lattice designs: re-entrant and double arrowhead auxetic structures, and a conventional non-auxetic honeycomb, which served as a reference. The lattices were fabricated from polycarbonate via Fused Filament Fabrication (FFF). Quasi-static compression tests were conducted to evaluate key crashworthiness metrics, including Energy Absorption (EA), Specific Energy Absorption (SEA), Peak Force (Pmax), Mean Crush Force (MCF), and Crush Force Efficiency (CFE). Finite element simulations were performed and validated against experimental data. Results demonstrate that lattice-filled tubes significantly outperformed empty tubes, with SEA enhancements ranging from 55% to 255%, depending on the lattice geometry. Notably, the non-auxetic honeycomb lattice achieved the highest EA, SEA, MCF, and CFE values, primarily due to its thicker cell walls and associated structural stiffness. These findings highlight the potential of engineered lattice fillers to enhance the crashworthiness of tubular structures under lateral loading.