3D Multidirectional Anisotropic Metastructure with Programmable Thermal Expansion, Poisson's Ratio, and Young's Modulus

Abstract

Maintaining the precise shape of spacecraft is particularly crucial for sophisticated instruments such as optical remote sensing satellites in the face of extreme temperature variations and high loads. To achieve the multifunctions of simultaneously programmable Poisson's ratio (PR) and coefficient of thermal expansion (CTE) in multidirections, this study proposes 3D multidirectional anisotropic metastructure (MAM) with programmable CET, PR, and Young's modulus based on the re-entrant structures and bimaterial trapezoid. The intrinsic mechanism of adjustable CTE and PR in bimaterial re-entrant structures is analyzed from the mechanical perspective. The theoretical method for Young's modulus in the y-direction is established based on Moor's theorem, and the accuracy of both the theoretical method and finite element analysis (FEA) results is verified through uniaxial compression tests. Then, the FEA results demonstrate that MAM can achieve directionally anisotropic adjustable CTE, PR, and Young's modulus by modifying the geometric parameters and material combinations. Furthermore, the mechanical responses of MAM under the thermomechanical load are investigated, achieving tunability of PR from positive to negative. This study offers a reliable reference for the design and optimization of engine components subjected to thermomechanical loads.