Laser powder bed fusion of node-reinforced hybrid lattice structure inspired by crystal microstructure: Structural feature sensitivity and mechanical performance

Abstract

Strut-based lattice structures (SLSs) have been widely used in modern industries including aerospace, automobile and biological implant, due to their unique properties such as lightweight, good energy absorption capability and high specific strength. However, the obtainable mechanical performance is significantly limited by the monotonous strut-based feature without any reinforcement topology. The inherent strengthening mechanisms and atom-scale models in material science may be crucial and valuable to optimize the complex structures with desired properties. Inspired by the solid solution strengthening mechanisms in crystal microstructure, a series of novel crystal-inspired hybrid structures, i.e., the common face-center cubic with Z-strut (FCCZ) structure, the face-center substitutional lattice (FCSL) structure, the edge-center interstitial lattice (ECIL) structure and the vertex-node substitutional lattice (VNSL) structure were designed and fabricated by laser powder bed fusion (LPBF) additive manufacturing in this work. The effect of node location on the LPBF formability, mechanical performance, stress distribution, deformation modes and failure mechanisms of the crystal-inspired components was systematically investigated. The computational fluid dynamics (CFD) method was used to understand the dynamics of molten pool to reveal the formation mechanism and control methods of the dross defect attached to overhanging surfaces. Finite element model (FEM) was established to show the stress distribution and deformation behavior of these hybrid structures during compression. Results showed that the ECIL structure possessed the highest specific energy absorption (SEA) of 13.7 J/g, which increased by 17% compared with the initial FCCZ structure. The crush force efficiency (CFE) of VNSL structure reached the peak value of 66% with a unique axisymmetric shear band during deformation, which increased by 14% compared to the FCCZ structure. The underlying mechanism analysis revealed that the as-designed spherical node could redistribute the stress and the performance of the lattice structures could be manipulated by tailoring the position of the spherical nodes. The present approach suggested that the hardening principles of crystalline materials could inspire the design of novel lattice structures with desired properties.