Functional gradient design of additive manufactured gyroid tantalum porous structures: Manufacturing, mechanical behaviors and permeability

This work proposes two types of tantalum porous structures with gradient changes in density and cell size along the forming direction via Laser Powder Bed Fusion (LPBF), utilizing simulation and experimentation to investigate the differences in mechanical behavior and permeability. The tantalum porous structures exhibited excellent printability with a porosity deviation between 0.406% and 5.13 %. The elastic modulus of the tantalum porous structures was similar to that of human cancellous bone, ranging from 215 MPa to 1103.67 MPa. The density gradient tantalum porous structures exhibited good impact resistance, while the negative effects of large size porous elements on the mechanical behavior cannot be ignored. The permeability ranged from 3.54 x 10-9-9 m2 2 to 11.39 x 10-9-9 m2, 2 , which is within the permeability range of cancellous bone. The cell-size gradient gyroid porous structures showed a lower inlet pressure (22.3 %-40.6 % reduction) and greater wall shear stress area between 20 and 30 mPa, which is conducive to the effective transport of nutrients, gases and decomposition metabolites. These findings offer a promising approach for achieving optimal biological performance and bone- matched elastic modulus through LPBF while providing guidance for the design of porous tantalum implants.