Compressive anisotropy of sheet and strut based porous Ti-6Al-4V scaffolds

Abstract

Porous metallic scaffolds show promise in orthopedic applications due to favorable mechanical and biological properties. In vivo stress conditions on orthopedic implants are complex, often including multiaxial loading across off axis orientations. In this study, unit cell orientation was rotated in the XZ plane of a strut-based architecture, Diamond Crystal, and two sheet-based, triply periodic minimal surface (TPMS) architectures, Schwartz D and Gyroid. Sheet-based architectures exhibited higher peak compressive strength, yield strength and strain at peak stress than the strut-based architecture. All three topologies demonstrated an orientational dependence in mechanical properties. There was a greater degree of anisotropy (49%) in strut-based architecture than in either TPMS architectures (18-21%). These results support the superior strength and advantageous isotropic mechanical properties of sheet-based TPMS architectures relative to strut-based architectures, as well as highlighting the importance of considering anisotropic properties of lattice scaffolds for use in tissue engineering.

Keywords: Additive manufacturing; Anisotropy; Lattice structures; Powder bed fusion; Ti–6Al–4V.