Effects of modeling strategies of triply periodic minimal surface on the mechanical properties and permeability of biomedical TC4 porous scaffolds

Modeling strategies play a crucial role in determining the unit shapes of triply periodic minimal surface (TPMS), significantly affecting the mechanical and permeability properties of porous scaffolds. In this study, two distinct strategies including surface thickening and surface filling were used to construct scaffold models based on four basic TPMS structures (Primitive [P], Gyroid [G], Diamond [D], and I-graph-wrapped package [IW-P]). These models were successfully prepared using TC4 alloy and selective laser melting technology. Macro/micro morphology, mechanical properties, and permeability tests of porous implants were carried out. The results indicate that the scaffolds effectively replicated the designed models, exhibiting mechanical properties that match those of human tissue. The elastic modulus ranges from 3.03 to 4.57 GPa, and the tensile strength varies between 135.78 and 250.90 MPa. The surface thickening strategy alters the material distribution within the unit, enhancing load uniformity on the scaffolds, thereby increasing the strength of the scaffolds with G, D, and IW-P units, while reducing stress fluctuations during compression. In contrast, the surface filling structure exhibits excellent permeability, with permeability rates falling within the range of 0.88 to 1.91 × 10-9 m2, aligning with the permeability performance of trabecular bone. This study offers new insights into the design of porous scaffold models tailored for various application scenarios.