Pre‐Torsion Tubular Metamaterials: Multi‐Effect Integration for Advanced Functional Applications

Abstract

Mechanical metamaterials continuously push the boundaries of mechanical properties far beyond conventional materials. However, a critical step toward the applications of metamaterials lies in combining multiple effects and functionalities into a single structure. Here, a pre‐torsion design paradigm is proposed to enable synergistic coupling of distinct mechanical properties. By incorporating such a paradigm into the auxetic tubular structures (ATSs), the robust and superior multi‐effect integration (MEI) performance consisting of compression‐torsion and auxetic effect under both axial compression and tension is achieved, and the underlying mechanisms are investigated numerically and experimentally. To further demonstrate their benefits in practical engineering, pre‐torsion auxetic nails are fabricated based on this design philosophy. Driving‐in tests have confirmed their MEI property and manifested extraordinary easy‐insertion and damage‐free performance. Compared to conventional nails, the pre‐torsion nail demonstrates a 52% reduction in energy consumption during wood penetration, along with a 27.1% decrease in initial peak force. This work bridges a crucial gap toward the applications of mechanical metamaterials and can be extended to various engineering scenarios for the design of functional structures and devices.