Designable dual-material auxetic metamaterials using three-dimensional printing

Metamaterials are inherently advantageous in achieving designable auxeticity since their Poisson' ratios are determined by the geometry of their unit cells. A family of auxetic metamaterials was created by computer-aided design (CAD) and dual-material three-dimensional (3D) printing. The effects of material selections and stiff material fraction on the Poisson's ratio, equivalent Young's Modulus, and maximum volume reduction were investigated. The results from finite element analysis (FEA) and mechanical testing indicated that the auxeticity and mechanical properties of this dual-material auxetic metamaterial (DMAM) are distinctly different from those of traditional single-material auxetic metamaterials (SMAMs). The interesting properties of DMAMs could be valuable to various engineering applications such as smart materials, biomedical components, and shock-resistant components.