A novel design of mono and bi-cells based hybrid auxetic structures and assessment of their compressive properties

Auxetic structures have evolved beyond conventional cellular structures by offering unique attributes, including lightweight design, auxeticity, and exceptional mechanical properties. These structures have attracted significant attention in the modern era, prompting the exploration of innovative structural designs and the hybridization of existing unit cells. These efforts involve designing modified and hybridized auxetic unit cells to achieve superior mechanical performance and auxetic characteristics. The Fused Deposition Modeling (FDM) fabricated auxetic structures are inherently anisotropic. To accurately model their mechanical behavior and reliably assess their performance through numerical modeling, anisotropy must be considered. This study addresses the design and development of various novel, modified, and hybridized auxetic structures, examining their mechanical behaviors through numerical and experimental methods. The necessary material constants are determined for numerical modeling following standard printing and testing practices. The analysis reveals that the novel structures exhibit excellent auxetic and mechanical properties. The anisotropic material model results are highly correlated with the experimental results, demonstrating high accuracy ranging between 0.3 % and 4.2 %. In contrast, the isotropic model deviates significantly from the experimental findings. This study has advanced the field significantly, resulting in observed improvements in mechanical properties ranging from 200 % to 800 %, but it has also established a procedural guideline for precise numerical modeling of auxetic structures.