Quasi-static lateral compression and energy absorption performance of dual-gradient auxetic honeycomb circular tube

Thin-walled circular tubes are widely used in crashworthiness and engineering safety. However, their compression performance under lateral loading is limited. Auxetic honeycombs have excellent energy absorption capacity and offer a promising alternative. Inspired by botanical gradient strategies and tubular shapes, the novel dual-gradient auxetic honeycomb circular tubes (AHCTs) are proposed. This study presents an innovative integration of dual-gradient design into a thin-walled auxetic tube for enhancing lateral energy absorption. Quasi-static lateral compression and energy absorption performances of AHCTs with different gradient strategies are analyzed. The optimal gradient design strategy of AHCT is further investigated. The results demonstrate negative thickness gradient and positive height gradient can effectively delay the onset of densification, while simultaneously shifting the main deformation mode of the AHCT from global plastic collapse to buckling of panels and cell walls. With comparison to the non-gradient design, the thickness and height dual-gradient configuration maximizes the AHCT's specific energy absorption by 138.9 %, work effectiveness by 310.6 %, and enhances stroke efficiency from 35.6 % to 61.1 %. These findings confirm that the proposed design significantly enhances the energy absorption performance of thin-walled structures and fills a critical research gap in lateral-resistant auxetic tube design.