Towards understanding the design principle and rotation deformation mechanics of 3D chiral NPR structure with tunable mechanical responses

Abstract

In this study, an innovative three-dimensional Negative Poisson’s ratio (NPR) chiral structure was designed based on a 2D staggered rib architecture. This design integrates horizontally oriented chiral alternating ribs and vertically oriented Z-shaped configurations. Two optimized architectures, namely the wave-optimized structure (W-NPR) and the node-enhanced structure (N-NPR), were proposed and compared with the original folded structure (F-NPR). Characterization analysis revealed that the N-NPR structure exhibited superior formability, making it suitable for Digital Light Processing (DLP) fabrication. A parametric study on the mechanical performance of the N-NPR structure demonstrated that an increased volume fraction enhances the mechanical properties at the expense of structural compliance. Uniaxial tensile testing along the XY-plane and Z-axis confirmed the anisotropic Young’s modulus. Experimental and finite element simulations further revealed anisotropic behavior and a unique two-stage rotation-torsion compressive deformation mechanism of N-NPR, which enables advanced mechanical designs by enhancing the degree of freedom for deformation mode conversion. This work proposes a novel method for designing 3D NPR structures and elucidates its mechanical deformation mechanism, enabling transformative advances in aerospace, personalized healthcare, and adaptive wearable technologies.