Revealing the apparent and local mechanical properties of heterogeneous lattice: a multi-scale study of functionally graded scaffold

Functionally graded scaffold (FGS) can flexibly regulate the mechanical properties of bone scaffold and holds great promise for offering multifunctional responses of orthopaedic implants. Heterogeneous FGSs constructed by skeletal and sheet triply periodic minimal surfaces (TPMSs) have been proposed in this study. The diversified deformation mechanisms of TPMS-FGSs showed superior mechanical stability, and energy absorption efficiency was enhanced by 3.0–79.0% and 2.6–16.8% compared to uniform skeletal and sheet TPMS, respectively. The graded structure of TPMS-FGSs altered the large-scale 45° shear failure to layer-wise or zigzag failure mode. Moreover, the comprehensive reformation of strain distribution and crack propagation in transition region under small compressive strain was experimentally and numerically studied. The results shed light on the global and local mechanical regulation mechanism of TPMS-FGS.