A synergistic design of composite metamaterial with drastically tailorable thermal expansion and Poisson's ratio

The artificially designed metamaterials can provide a possibility to achieve excellent mechanical properties such as negative coefficient of thermal expansion (CTE) and negative Poisson's ratio (PR) due to its unique geometric microstructure. In this paper, we introduce the concept of combination deformation of bi-material into the re-entrant structure and design a metamaterial with both customizable negative PR and adjustable CTE. The relationship between the relative density and the geometric parameters of the 3D metamaterial is explored to show the excellent lightweight characteristics of the material. It is found that the relative densities of the designed materials are lower than 3%. In addition, the theoretical analysis and finite element method are used to reveal the deformation mechanism of the metamaterials. The results show that the PR and CTE of the metamaterials can be precisely tailored by adjusting the geometric parameters of the microstructure. Different combinations of the component materials can drive continuous change of the CTE from positive to negative. This synergistic method can be applied to design macro-, micro- and meso-structures of the metamaterials which have significant potential application in aerospace, biomedicine.