Ni-Ti multicell interlacing Gyroid lattice structures with ultra-high hyperelastic response fabricated by laser powder bed fusion

Ni-Ti alloys based on triple-periodic minimal surface lattice metamaterials have great application potential. In this work, the triply periodic minimal surface (TPMS) lattice structures with the same volume fraction from a normal Gyroid lattice to an octuple interlacing Gyroid lattice were prepared by the laser powder bed fusion (LPBF) technique. The influence of the interlacing-cell number on manufacturability, uniaxial compression mechanical behaviors, and hyperelastic responses of Ni-Ti lattice structures are analysed by experiments. The stress distributions and fracture mechanism of multicell interlacing lattice structures are illustrated by the finite element method. The obtained results reveal that when the volume fraction is the same, the specific surface area of the lattice structure increases with increasing interlacing-cell number, and the curvature radius of the singlecell strut reduces, which leads to the decrease in the manufacturability of the lattice structure. Meanwhile, the diameter of the single cell strut decreases, and the stress it can bear decreases, which leads to a decline in the compressive mechanical property of the lattice structure. However, the number of struts increases with the increase of interlacing cells, which makes the stress distribution of the lattice structure more uniform. The cyclic compression results indicate that with increasing interlacing-cell number, the proportion of the hyperelastic recoverable strain increases, and the residual strain in the cyclic compression test decreases. For the lattice structure with a chiral arrangement of single cells, the manufacturability, compressive mechanical properties, and hyperelasticity are comparable to those with a normal arrangement. Notably, the Ni-Ti Gyroid TPMS lattice structures have superior hyperelasticity properties (98.87-99.46 % recoverable strain).