The quasi-static responses and variable mechanical properties of a novel 3D composite auxetic tubular structure connected by the thin-walled tube

In this paper, a novel 3D composite auxetic tubular structure (3D CATS) connected by a thin-walled (TW) circular tube was proposed, and two sets of parameters h1, h2, and beta, n were introduced to construct structural families with various geometries and mechanical properties. The mechanical responses of the 3D CATS were preliminarily explored through the quasi-static experiment. The good agreement between the experimental results and the finite element (FE) simulation verified the accuracy of the FE model. Subsequently, the coupling mechanism between the tube and auxetic units was revealed by analyzing the deformation modes and force responses. The results indicated that the deformation of auxetic units caused more plastic hinges in the tube to enhance the contact force seriously. Then, the 3D CATS was proved to exhibit better specific energy absorption (SEA) compared with other auxetic structures. Furthermore, the influence of h1, h2, and beta, n on the responses was also discussed. The results showed that h1, h2 can change the compression displacement points and forces, while beta, n can adjust the stiffness and forces. The results can provide an important reference for the design and study of variable mechanical properties for innovative 3D auxetic structures with enhanced performance.