3D-printed Lunar regolith simulant-based geopolymer composites with bio-inspired sandwich architectures

Over time, natural materials have evolved to be lightweight, high-strength, tough, and damage-tolerant due to their unique biological structures. Therefore, combining biological inspiration and structural design would provide traditional materials with a broader range of performance and applications. Here, the application of an ink-based three-dimensional (3D) printing strategy to the structural design of a Lunar regolith simulant-based geopolymer (HIT-LRS-1 GP) was first reported, and high-precision carbon fiber/quartz sand-reinforced biomimetic patterns inspired by the cellular sandwich structure of plant stems were fabricated. This study demonstrated how different cellular sandwich structures can balance the structure–property relationship and how to achieve unprecedented damage tolerance for a geopolymer composite. The results presented that components based on these biomimetic architectures exhibited stable non-catastrophic fracture characteristics regardless of the compression direction, and each structure possessed effective damage tolerance and anisotropy of mechanical properties. The results showed that the compressive strengths of honeycomb sandwich patterns, triangular sandwich patterns, wave sandwich patterns, and rectangular sandwich patterns in the Y-axis (Z-axis) direction were 15.6, 17.9, 11.3, and 20.1 MPa (46.7, 26.5, 23.8, and 34.4 MPa), respectively, and the maximum fracture strain corresponding to the above four structures could reach 10.2%, 6.7%, 5.8%, and 5.9% (12.1%, 13.7%, 13.6%, and 13.9%), respectively.