Improved light-weighting potential of SS316L triply periodic minimal surface shell lattices by micro laser powder bed fusion

Abstract

Micro laser powder bed fusion (μLPBF), for the first time, enables fabrication of low-density triply periodic minimal surface (TPMS) shell lattices with smaller feature size. However, the understandings on the mechanical responses of lightweight TPMS structures by μLPBF are yet to be updated. Herein, stainless steel 316L TPMS shell lattices (i.e., Primitive (P), Diamond (D) and Gyroid (G)) with different shell thicknesses and cell orientations were fabricated by µLPBF. Low-density TPMS structures with shell thickness as small as ∼100 μm and relative density ∼5 % were realized. Quasi-static compression tests and finite element modelling were conducted to study their compressive responses. Their light-weighting potential related to the scaling behavior of mechanical properties as a function of relative density was analyzed. Results show with increasing relative density, the deformation mechanism transforms from localized collapse to homogeneous bulk deformation. P-type TPMS exhibits the highest anisotropy of stiffness, strength and energy absorption capability, while G-type TPMS is near-isotropic. [100] oriented d-type TPMS shows the highest strength and best light-weighting potential. Compared with conventional LPBF, the µLPBF TPMS structures demonstrate higher mechanical properties and superior light-weighting potential. Overall, this work highlights the superiority of the µLPBF technology in fabricating lightweight TPMS structures for mechanical applications.