Full compression response of FG-based scaffolds with varying porosity via an effective numerical scheme

Abstract

The triply periodic minimal surfaces (TPMS) can be employed to realize the variable porosity gradient in different directions and has a great application prospect in the orthopedic implant field. In the present scrutiny, two kinds of gyroid-based TPMS gradient scaffolds (skeletal-gyroid and sheet-gyroid) in different orientations are established and manufactured by utilizing selective laser melting (SLM) technology with Ti-6Al-4V powders. The meshing of the TPMS based on the voxelization loses its surface smoothness and brings the geometric defects of steps. Therefore, an optimized smoothing-tetrahedral mesh strategy (STMS) to finite element analysis (FEA) is proposed to explore the graded scaffolds’ overall deformation response and energy absorption efficiency. The obtained results reveal that the mechanical properties of the samples are slightly altered after heat treatment. The sheet-gyroid (Sh-G) structure has a higher elastic modulus and compressive strength, more stable energy absorption efficiency, and higher total energy absorption compared with the skeletal-gyroid (Sk-G). The fracture morphology of the Sk-G exhibits two distinct regions: a typical dimple of ductile fracture and a brittle fracture characterized by the flow pattern, while the Sh-G samples only demonstrate brittle fractures. The STMS and Johnson-Cook plastic damage model correctly simulated the gradient porous scaffolds’ plastic deformation and failure behavior after yielding. Furthermore, the stress-strain curves of the simulation agree well with the experimental results such that the minimum elastic modulus and yield strength discrepancies in order are 0.5 and 2.8%. The STMS improves the simulation accuracy of the TPMS structure and provides a solid foundation for designing and applying artificial bone scaffolders in the near future.