A novel orthogonal anisotropic auxetic structure with enhanced auxeticity

• A novel orthogonal anisotropic auxetic structure with enhanced auxeticity (ESEA) was obtained through topology optimization. • Different initial design domain and optimization parameters were used to explore more topology configurations. • Experiments and numerical analysis were conducted to comprehensively study the mechanical properties and energy absorption of the novel structure. • The structure shows enhanced auxeticity and stiffness compared to other studies. Auxetic structures have been utilized in various fields due to their unique deformation patterns and functional versatility. However, most research has focused on isotropic auxetic structures. Orthogonal anisotropic auxetic structures, which can exhibit a negative Poisson's ratio below -1 in a single direction, have not been thoroughly investigated, despite their unique applications in vascular stents, sensors, piezoelectric energy harvesters and many other fields. In this study, a novel orthogonal anisotropic auxetic structure with enhanced auxeticity (ASEA) was obtained through topology optimization using a modified SIMP method and an energy-based homogenization approach. Different initial design domains and varied topology optimization parameters were employed to mitigate the influence of optimization parameters on the final results and to discover more topological configurations. The Poisson’s ratios of the obtained unit cells were calculated using the energy homogenization method. The unit cell with the minimum auxetic ratio was selected and simplified for subsequent parametric design and analysis. Subsequently, quasi-static compression tests and finite element simulations were conducted to investigate the deformation, energy absorption, and Poisson's ratio properties of the structure. The influence of structural parameters on the structural properties was thoroughly studied. Results show that the Poisson's ratio of the structure could reach -4 to -6 in the elastic stage and then decay rapidly to 0 with increasing strain. The mechanical properties of the structure are programmable by altering the structural parameters. This study provides a new approach to designing anisotropic auxetic structure with enhanced auxeticity.