Arapaima-inspired NiTi bionic lattice structures with excellent energy absorption and splendid recoverability fabricated by laser powder bed fusion

Bionic lattice structures with high-energy absorption and compression reversibility play crucial roles in aerospace and other engineering applications. However, the realization of these functions depends heavily on the material selection and structural design. In this study, two types of bionic structures, a Bionic Lattice Structure (BLS) and a Bionic Lattice Cubic Structure (BLCS), were prepared by Laser Powder Bed Melting (LPBF), inspired by Arapaima scales, and combined with NiTi shape-memory alloys. Quasistatic compression, cyclic compression, and recovery tests were conducted to investigate the energy absorption performance and reusability of the different structures. The results revealed that BLCS exhibited an excellent Specific Energy Absorption (SEA) response, which was almost double that of BLS, while local fractures occurred when the strain reached 13 %. Interestingly, the strain value of BLS reached 25 %. Therefore, by combining the advantages of the two bionic structures, improvements were made to the BLCS and a hybrid structure with various configurations was achieved through the integration of the BLS. The fracture strain and recovery rate of the lattice structure were 25 % and 98.2 %, respectively. Meanwhile, the SEA of lattice structure increased by 124 % and 16 % compared of with those of BLC and BLCS. Ultimately, a numerical simulation was applied to optimize the analysis of the structures, which indicates that the SEA of the structure increases as a function of wall thickness and spiral angle. This study offers a strategy for achieving exceptional energy absorption performance and repeated energy absorption at high-compression strains in NiTi bionic structures. Simultaneously, it is expected to promote the engineering applications of this bionic multifunctional NiTi alloy structure with both high-energy absorption and high-recovery characteristics.