MECHANICAL PERFORMANCE of POROUS IMPLANT with DIFFERENT UNIT CELLS

This study investigates the effect of different unit cells on the mechanical performance of porous implant. Three shapes of unit cells (Diamond 30(DO30), Octet truss 30(OT30), and Rhombic dodecahedron 30(RD30)) were selected, which have the same relative density. Corresponding models of single pore (SP), repeating pores (RP) and porous implant (PI) were created. Using finite element methodology, mechanical performances of three classes of models under the conditions of pressure and torsion were simulated based on the same static load (SP: 50N, 0.125N·m; RP: 200N, 0.5N·m; PI: 200N, 0.5N·m), respectively. Results demonstrated that RP showed consistent mechanical performances with SP: OT30 displayed the lowest stresses, displacements, and strains under the conditions of pressure and torsion, and conversely DO30 always resulted in the highest magnitudes. For the case of PI, mechanical performances were different from SP and RP: implant with shape of RD30 resulted in the lowest stress (275.2MPa) under the condition of pressure, but displacement (2.236e-002mm) and strain (3.050e-003) of OT30 were the largest; under the condition of torsion, stress sequence was same as SP and RP, but DO30 provided the highest strain (2.437e-003), RD30 displayed the largest displacement (1.508e-002mm). Unit cell influences mechanical performance of porous implant directly, and the implant outline and incomplete structure may also affect it. It could not select pore simply by the right type of unit cell, and surface area is an important parameter as well as pore size.