Compressive properties and fatigue performance of NiTi lattice structures optimized by TPMS

Abstract

Nickel titanium (NiTi) lattice structures prepared by laser powder bed fusion (LPBF) have great application potential, due to their unique shape memory effect, superelasticity, and controlled geometry characteristics. In this study, the NiTi I-graph-wrapped package (I-WP) and NiTi body-centered cubic (BCC) lattice structure samples were prepared by the LPBF process. The uniaxial compression properties and cyclic compression properties of NiTi lattice structure samples prepared by LPBF process were studied. The results showed that the surfaces of NiTi lattice structures were very rough and adhered with many powder particles. The sample optimization design through the minimal surface could effectively improve the mechanical properties and deformation resistance and change the surface morphology of fracture surfaces in high cycle fatigue. The I-WP lattice structure had a higher Young’s modulus and yield strength. The fatigue strength improved from 1.88 MPa (BCC structure lattice) to 2.08 MPa (I-WP structure lattice). The simulation was performed to investigate the mechanism underlying the improvement in fatigue strength, revealing that optimization of surface stress distribution could be the plausible reason. In general, this study provides valuable guidance for the preparation and design of NiTi lattice structure by the LPBF process.