Laser powder bed fusion of diatom frustule inspired bionic NiTi lattice structures: compressive behavior and shape memory effect

This work aimed to propose a feasible lattice structure to fully exploit the advantages of NiTi shape memory alloy, providing more options for the development of functional components such as micro-vibration isolators and smart actuators in the aerospace field. Inspired from the Campylodiscus diatom frustule, the novel NiTi-based truss lattice structures were designed and fabricated by laser powder bed fusion. Four lattice structures with different ratios of traditional sharp angle (TSA) number to bionic arc angle (BAA) number (xi (TSA/BAA)) were designed and the effect of the xi (TSA/BAA) on the compressive behaviors and shape memory effect (SME) was experimentally investigated and the failure mechanism was revealed using finite element (FE) simulation. Results showed that all components possessed a nearly dense microstructure (>98%) and high dimensional accuracy (size error < 2.5%). As the ratio of the number of TSA to BAA decreased, the maximum first peak force decreased by 31.5%, and the elastic modulus E-epsilon (=0.2%) decreased from 1.81 GPa to 1.19 GPa. And the failure modes changed from layer-by-layer failure to shear failure. The simulation results were in agreement with the experimental results and revealed that the xi (TSA/BAA) affected the compressive behaviors by controlling the stress value and distribution of components. Results of SME tests showed that the introduction of BAA design can improve the recovery performance, and the xi (0/6) component exhibited the largest recoverable ratio and the lowest accumulated residual strain.