Near-zero thermal mismatch flexure metastructure with high-resonant frequency

Heterogeneous mechanical metastructures, especially fabricated by additive manufacturing techniques, have attracted attention in lightweight multifunctional material engineering. Near-zero thermal expansion materials play an important role in precision equipment. However, undesired thermal mismatch flexure distortion occurs when the precision equipment is mounted on the main load-bearing structures of spacecraft and the environmental temperature changes. The present study presents a near-zero thermal mismatch flexure metastructure, including the design strategy inspired by plants with axisymmetric distributing anisotropic microstructures, the thermal deformation constitutive relation derived by the flexibility method, and the fabrication of this metastructure by selective laser melting. Thermal deformation experiments demonstrate that the coefficient of thermal flexure reduces by 92.4% compared with traditional bi-material plates connected by screws. Mechanical vibration experiments demonstrate that the fundamental resonant frequency of this metastructure can be as high as 956 Hz, which is 5.8 times larger than the common requirements of functional components for spacecraft to avoid mechanical resonance with the main structure during launch. The excellent thermal mismatch shape stability and high-resonant frequency properties make it a potential candidate for thermal geometric stable structures working in variable thermal and mechanical environments.