Elastic mechanical properties of a novel auxetic mechanical metamaterial inspired by tubular Origami

This study introduces a novel three-dimensional thin-walled auxetic mechanical metamaterial. The structure integrates Origami design principles with a tubular honeycomb geometry. The design merges the benefits of auxetic mechanical metamaterial, the lightweight efficiency of honeycombs, and the geometric adaptability of Miura tubular Origami. The in-plane and out-of-plane elastic properties, such as Poisson's ratio and normalized Young’s modulus, are systematically examined for both single-cell and full-scale auxetic honeycomb structures. Finite element simulations were performed on these structures, and a representative volume element (RVE) was derived from the full-scale model for comparative analysis. The numerical models were validated through compression tests in accordance with ASTM standards. A parametric study assessed the effect of geometric parameters on mechanical performance. Results show the single-cell model achieves an experimental negative Poisson's ratio (NPR) of -1.03 with a normalized Young’s modulus of 0.02 and specific modulus of 0.12, while the full-scale model reaches an NPR of -0.59 with a normalized Young’s modulus of 0.0252 and specific modulus of 0.21. Architectures with unit cell radii greater than 20 mm exhibit auxetic behavior in both transverse and in-plane directions, demonstrating high stiffness and significant NPR capabilities. Notably, the in-plane normalized stiffness of the origami-based metamaterial is up to ten times greater than that of analogous hexagonal honeycombs with equivalent unit cell parameters. Furthermore, an Ashby-type comparison shows that the proposed structure simultaneously achieves a more negative Poisson’s ratio and higher normalized Young’s modulus, highlighting both its superior performance and structural novelty.