Numerical and experimental study on the energy absorption characteristics of thin-walled auxetic cylindrical tubes with varying porosity

Abstract

A numerical and experimental combined study was carried out to examine the crushing behavior and energy absorption of steel auxetic thin-walled cylindrical tubes under quasi-static axial compression. Fifteen new auxetic designs with Cylindrical Lozenge Grid (CLG), Cylindrical Square Grid (CSG), and Cylindrical Peanut Grid (CPG) patterns were created, five of which were fabricated for experiments. Validated finite element simulations examined the effect of pattern type and porosity (through cell rib thickness) on Specific Energy Absorption (SEA), Peak Crushing Force (PCF), Mean Crushing Force (MCF), and Crush Load Efficiency (CLE). The "auxetic effective crushing length" was defined to measure the optimal deformation before cylindrical buckling. In this stage, CLE was 80–100 % while SEA was low (0.5–1.5 J/g). Complete crushing up to 60 mm displacement raised SEA to approximately 6 J/g but reduced CLE to 20–60 %. Reduced porosity increased SEA, PCF, and MCF but reduced the auxetic effective crushing length from approximately 33 mm (CLG-1.5) to 8 mm (CLG-3.5). Increased porosity encouraged more progressive, stable energy absorption. Pattern type and rib thickness were identified to significantly influence auxetic deformation, failure mode, and energy dissipation. These quantitative findings give insights for the design of lightweight energy-absorbing structures, prioritizing controlled and predictable deformation over absolute energy absorption, for crashworthiness and impact mitigation applications.