Auxetic Behavior and Mechanical Properties of a New Negative Poisson's Ratio Structure Based on Swallowtail Butterfly Biomimicry

Negative Poisson's ratio (NPR) structures excel in enhancing fracture toughness, enabling lightweight design, and improving indentation resistance, while conventional structures suffer from compressive instability and low energy absorption efficiency. To balance structural lightweighting, compressive stability, and energy absorption, this study proposes a novel bio‐inspired NPR honeycomb (SBH) based on swallowtail butterflies’ stable flight under multidirectional airflow impacts. Composed of periodically arranged swallowtail butterfly–inspired unit cells linked by transverse supporting ribs, SBH exhibits stable compressive deformation, a distinct NPR effect and orderly densification under compression. An enhanced variant (SBEH) is further designed to optimize energy absorption capacity. Quasi‐static compression experiments validate the finite element model, and theoretical analysis integrating the ideal rigid‐plastic model and energy conservation principle deduces SBEH's plateau stress theoretical solution. Parametric analysis investigates the effects of wall thickness, supporting rib length and aspect ratio on SBH and SBEH's deformation modes, NPR effect, and energy absorption, laying a foundation for performance‐tailored parametric design. Results show SBH features remarkable NPR characteristics and stable compressive deformation but insufficient energy absorption, while SBEH retains these merits and achieves superior energy absorption. This work provides a novel design concept for high‐efficiency energy‐absorbing mechanical metamaterials with excellent compressive stability.