A novel hierarchical auxetic star-shaped honeycomb with enhanced stiffness

Auxetic structures have garnered significant research attention owing to the exceptional mechanical properties and distinctive negative Poisson’s ratio. Nevertheless, the inherent high porosity of such lattice structures leads to a reduction in stiffness, which significantly limits their practical engineering applications. Moreover, most current approaches significantly increase the overall mass and compromise the auxetic effect. In our previous work, we introduced a novel hierarchical auxetic star-shaped honeycomb (HASS). This design integrates the concept of hierarchical structuring by introducing an additional internal star shape, rotated 45°, within the traditional star-shaped structure (TSS), thereby providing improved mechanical support. The modification has been demonstrated to significantly improve energy absorption performance. To conduct a systematic investigation of HASS, this study employs the matrix displacement method to derive analytical solutions for its elastic modulus, establishing a theoretical basis for its practical implementation. To mitigate the confounding effects of mass on stiffness, a comparative analysis of specific stiffness and Poisson’s ratio between the HASS and conventional structures is performed through an integrated approach combining finite element simulations and experimental measurements. Additionally, a systematic study is carried out to explore how geometric parameters affect the mechanical behavior of the structures. The results indicate that the specific stiffness and auxetic characteristics in specific directions of the HASS are significantly enhanced, effectively compensating for the limitations inherent in conventional optimization designs. This study offers innovative perspectives for the design and optimization of honeycomb structures, advancing the development of more efficient and high-performance structural configurations.