Origami-Inspired innovative auxetic structures for nails and screws : tensile and compressive performance analysis

Abstract

Auxetic structures, also known as negative Poisson’s ratio (NPR) structures, exhibit programmable deformation characteristics. Certain origami structures, designed with precisely crafted creases and selected materials, can form complex three-dimensional shapes. When external forces are applied, these structures inherently exhibit NPR properties. By leveraging the synergy between origami structures and NPR characteristics, a novel type of nail and screw can be designed. The auxetic nature allows nails to contract upon hammering, minimizing friction for seamless insertion, and to expand when pulled out, enhancing grip and security. For screws, contraction under compressive forces alleviates insertion challenges, while expansion under tensile forces inhibits loosening. This study validates the introduction of origami into the design of porous nails and screws through simulation and experimentation, employing a combination of finite element analysis and experimental methods, this study systematically investigates the influences of origami patterns (such as re-entrant origami and double arrowed origami), angle parameters, and threads on the structural mechanical properties. The results indicate that incorporating three-dimensional origami units into the structure increases both stiffness and peak force by over 50% compared to traditional auxetic structures. Furthermore, the NPR property is found to be 350% greater than that of conventional structures.