An improved in-plane dynamics analysis of auxetic star structures enhanced with self-similar inclusions

This paper presents an extensive mechanical and deformation characterization of the stiffness and energy harvesting of the proposed modified star-shaped auxetic honeycomb structure (MAHS), reinforced with self-similar inclusions (SSIs). The consequences of two SSI arrangements (MAHS-I and MAHS-II) on the crashworthiness and auxetic performance of the MAHS are systematically investigated in a comparative manner. Quasi-static uniaxial compression tests were conducted to verify the theoretical models of the MAHS, and the experimental results were in good agreement. A series of parametric studies revealed that the MAHS-I exhibits better auxeticity at high speeds, while the opposite is true for stiffness. The apex angle of the star-shaped honeycomb and the apical angle of the SSI show facilitating and weakening actions, respectively, on the auxeticity of the MAHS. Compared to the conventional star-shaped auxetic structure, both the stiffness and the consistent auxeticity were greatly promoted. This study provides an effective and feasible solution for the design of new auxetic structures and contributes to the application of auxetic metamaterials in shielding engineering.