Comparative Study on Pore Characteristics and Mechanical Properties of Solid and Sheet TPMS Models / 医用生物力学

ABSTRACT

Objective To analyze and compare pore characteristics and mechanical properties of models with solid and sheet triply periodic minimal surface (TPMS) structures, and build a porous structure with high specific surface area, low stiffness and high strength. Methods The solid TPMS and sheet TPMS models of D, G, and P units with the same porosity were established, and pore characteristics of the model such as pore diameter, rod diameter and specific surface area were compared; mechanical properties of the model were analyzed by finite element method. The porous titanium samples were made by additive manufacturing technology, pore characteristics of porous titanium were observed by microscope and scanning electron microscope, and mechanical properties of porous titanium were detected by compression test. Results The specific surface area of the sheet structure with the same unit was significantly higher than that of the solid structure; mechanical properties of the sheet structure with the same were significantly better than those of the solid structure. Among them, the D unit sheet TPMS model had the most significant advantages, with the specific surface area of 13.00 mm-1, and the elastic modulus, yield strength and compressive strength of the sheet porous titanium sample were (5.65±0.08) GPa, (181.03±1.30) MPa and (239.83±0.45) MPa, respectively, which were 43.87%, 55.08% and 67.21% higher than those of the solid porous titanium sample. Conclusions While retaining low rigidity of the porous structure, the sheet TPMS model of the same unit has a larger specific surface area, which is beneficial for cell adhesion and growth, and its low stiffness and high strength mechanical properties can effectively reduce stress shielding and provide sufficient mechanical support. It is an ideal pore structure model for bone defect repair substitutes.