An Unusual 3D Metamaterial with Zero Poisson's Ratio in Partial Directions

Materials with an abnormal Poisson's ratio, including those with negative Poisson's ratio (NPR) and zero Poisson's ratio (ZPR), are an important category of mechanical metamaterials, among which many exhibit NPR in all three directions. However, few of them, especially the 3D materials, exhibit ZPR in partial directions and NPR in other directions. Herein, a novel 3D structure developed by orthogonal splicing the 2D parallelogram honeycomb structure is proposed. Different from the 2D parallelogram honeycomb with ZPR, the spliced 3D parallelogram structure can exhibit not only ZPR but also NPR in different directions. The analytical model of the structure is established based on the classical beam theory, the equivalent analytical formulas of Young's modulus and Poisson's ratio are given, and finite element simulation and experiments are used for verification. The relationships between Young's modulus and Poisson's ratio of the structure, as well as its geometric parameters and material parameters, are analyzed using analytical formulas and numerical simulation. The results reveal that the structure is transversely isotropic and can achieve NPR on the transverse symmetry plane and ZPR outside the plane. This unique property may accord this structure with important applications in aerospace, biomedical, and other fields.

Automated summary

A novel 3D structure with both ZPR and NPR is proposed by splicing the 2D parallelogram honeycomb structure orthogonally. The structure exhibits different Poisson's ratios in different directions, and its properties are verified through finite element simulation and experiments. This structure may have important applications in aerospace, biomedical, and other fields.