The structure design and application of metamaterials with negative Poisson's ratio

Metamaterials with negative Poisson's ratio, also called auxetic metamaterials, are artificially engineered structures or materials that possess extraordinary auxetic effect, high shear modulus, excellent impact resistance, and remarkable energy absorption capability. They have been widely applied in aerospace, transportation equipment, mechanical automation, and biomedical engineering. The unique properties of metamaterials are generally determined by the geometry and arrangement of their unit cells. However, due to the structural complexity and microscale dimensions of these cells, traditional manufacturing methods often fail to meet precision requirements, which has significantly restricted research progress in this field. In recent years, with the continuous advancement and maturation of additive manufacturing technology, it has become possible to fabricate complex and delicate microstructures, providing new opportunities for the development and practical application of auxetic materials. This paper focuses on the deformation mechanisms, mechanical properties, and structural characteristics of auxetic metamaterials. It provides an in-depth summary of the physical models of auxetic unit cells, such as re-entrant polygon and rotating rigid unit structures, and explores their wide applicability. Finally, the challenges and future prospects of auxetic metamaterials are summarized, aiming to provide valuable insights and references for the further development and practical applications of auxetic metamaterials and structures.