A multifunctional mechanical metamaterial with adjustable density, stiffness, Poisson’s ratio, and thermal expansion

Mechanical metamaterials have garnered significant attention in materials and mechanics due to their unique geometric designs and tunable properties. However, metamaterials that allow for simultaneous multi-parameter control remain relatively scarce. This study introduces a multifunctional mechanical metamaterial where density, Young’s modulus, Poisson’s ratio, and thermal expansion coefficient are coordinately tunable through a combination of geometric design and material distribution. The influence of geometric and material parameters on the effective properties of the proposed metamaterial was systematically investigated through analytical solution, finite element simulation and experimental measurement. The results demonstrate that adjusting geometric parameters enables the structure to achieve a combination of lightweight characteristics, high adaptability, and negative Poisson’s ratio. Furthermore, the introduction of heterogeneous materials, leveraging the thermal strain mismatch at their interfaces, allows for simultaneous control over the structure’s thermal deformation, enabling either negative or positive thermal expansion. These combined properties are difficult to achieve with existing natural or artificial materials. This work can provide potential applications in flexible devices, smart structures, and thermal management.