3D printed functionally graded hollow lattice structures: Multi-dimensional design for large deformation

This study investigates uniaxial and multidimensional thickness grading strategies for designing hollow lattice structures based on the octet-truss topology, focusing on materials like Al-Si10-Mg and SS316L. Fabrication, quality examinations, homogenization techniques, finite element modelling, and compressive tests were used to analyse these structures. Functionally graded hollow octet-truss lattice structures exhibit continuous hardening without stress softening after yielding points. The multidimensional functionally graded design consistently demonstrated superior mechanical properties with cubic symmetry, including effective yield strength and plateau stress, and excelled in mitigating stress shielding effects and shear band formation. The multi-dimensional functionally graded design also showed efficient load transition and consistent performance across different materials. When applied with less ductile base material such as Al-Si10-Mg, its mixed stiff-soft interactions provided mitigation of excessive local bending deformation on struts, outperforming other designs with a specific energy absorption (SEA) of 29.90 J / g and plateau stress of 52 M P a . These findings highlight the potential of functionally graded hollow octet-truss lattice structures for applications such as implants, crash protection, and impact resistance, offering valuable insights for developing advanced lattice structures.