Compression-torsion coupling auxetic tubular structures with enhanced stability

Auxetic materials exhibit exceptional mechanical properties and distinctive deformation characteristics. A novel compression-torsion coupled auxetic tube is introduced in this study, which integrates an auxetic structure with a compression-torsion coupling mechanism. By modifying the inner tube and ribs of the structure, the compression-torsion coupling effect is enhanced, improving both the mechanical properties and deformation characteristics. Three compression-torsion coupled auxetic tubes (CATs) were fabricated using 3D printing technology. They were compared with conventional auxetic tubes (AT) to examine the influence of compression- torsion coupling on structural behavior. Experimental results were compared with simulation, confirming the validity of the finite element model. Numerical analysis was conducted to investigate the influence of the direction of compression-torsion coupling and outer wall thickness on CAT structures. The results demonstrate that the compression-torsion coupling effect changes the wall thickness under compression, enhancing energy absorption and structural stability. The structure has a densification delay of 28.5 % compared to other perforated tubes, and the SEA has increased by 105 %. Additionally, the application of compression-torsion coupled auxetic tubes in auxetic springs was explored, revealing that the compression-torsion coupling effect significantly prolongs the working displacement of the structure while improving its capacity for elastic energy storage. CAT has broad application prospects in the fields of soft robots and protective engineering.