Experimental and numerical analysis of a novel assembled auxetic structure with two-stage programmable mechanical properties

A costly and inefficient manufacturing process significantly impedes broad applications of auxetics. Herein, a novel fabrication methodology based on assembling plates and tubes is presented. Instead of fabricating auxetic structures by regularly-used 3D printing and laser cutting techniques, inexpensive commonly-used materials were assembled by adhesive in a portable way. Quasi-static compression test was carried out experimentally and numerically. Based on reliable finite element models, parametric study and gradient design were conducted for structural optimization. Numerical results reveal the significance of each geometric parameter and give evidence of the advantages of gradient design. The proposed structures are not only favorable in mechanical performance in terms of multi-stage densification and programmable stiffness and strength, but also promising in low-cost and large-scale fabrication. Such a fabrication methodology has great potential in applications of auxetic structures in protective equipment and smart energy absorbers.