Space Structure Building Block Inspired by Deep-Sea Glass Sponges

Large Space Structures are a vital component of upcoming space missions and space exploration ambitions. A recent automated construction paradigm made of modular lattice elements (building blocks) and relative robots has become a viable approach to constructing ultra-large multi-functional space structures. However, when undergoing on-orbit construction and operating in disturbance load conditions, the free-free floating space structures experience continuous surface deformation or vibration. Spatial platform instability would inevitably affect the construction speed, assembly reliability, and construction agent design complexity. Herein, aiming for a lightweight, high specific stiffness structure with excellent compacting stowage, we propose a novel robust building block design inspired by deep-sea glass sponges which feature hierarchical architecture and outstanding buckling resistance. To study the sponge's skeletal architecture mechanical advantages for three-dimensional building blocks, we analyze the performance enhancement with simple-cube and cube-octahedron (or simple-voxel) through the combination of finite element simulations and mechanical tests. The building blocks with and without sponge reinforcement are fabricated via micro-3D printing with up to 50µm resolution to achieve the required accuracy. Both numerical analysis and compression tests are used to assess stiffness as well as specific stiffness performance for various building block designs. More specifically, uniaxial compression tests are simulated using ABAQUS to gain insights into local buckling behavior. In addition, various lattice block sizes (up to 7x7x7) are analyzed to predict the performance of large-scale space structures. When considering the volumetric mass of different block designs, the analysis results show that simple-voxel design offers the most preferrable specific stiffness performance. This is further confirmed through a case study of a large solar-array structure.