Compressive properties and energy absorption of selective laser melting formed Ti-6Al-4V porous radial gradient scaffold

Uniform porous structures are widely considered as the biological implant materials, but they are difficult to meet the needs of complex bone transplantation. The radial gradient porous structure can match the mechanical properties of different levels of natural femur by adjusting the internal and external porosity. Based on Gyroid unit cells, a parameterized model was employed to create a biomimetic bone structure. Uniform porous structure with an average porosity of 50% and radial gradient porous structure were prepared by selective laser melting (SLM).The mechanical properties, deformation behavior and energy absorption properties of uniform and radially graded porous structures were studied by compression test and finite element method (FE).The results show that the compression test curves of all porous structure exhibit elastic stage, platform stage and densification stage. In the platform stage, uniform porous structures are prone to early shear failure and poor energy absorption performance, whereas radially gradient porous structures exhibit higher elastic modulus and yield strength. When the strain is 0.3, uniform porous structures and porous structures with an inner porosity of 80% mainly exhibit 45° flexural-shear failures, while radially gradient porous structures with inner porosity of 62.5% and 70% experience V-shaped shear failures. Porous structures with an inner porosity of 70% have good energy absorption (107.99 MJ/m3), maximum energy absorption efficiency (46.94%), elastic modulus (5.2 GPa), and yield strength (296.02 MPa), matching the demands of cortical bone. [Display omitted] •The parametric model accurately expresses the radial gradient characteristics.•SLM can accurately form radial gradient porous structure.•Inner and outer layer porosity differences affect the mechanical performance.•The mechanical performance of radial gradient is superior to uniform structure.•Radial gradient pore distribution improves energy absorption and toughness.