Morphological and mechanical characterisation of three-dimensional gyroid structures fabricated by electron beam melting for the use as a porous biomaterial. (January 2022)

• Record Type: Journal Article
• Authors: Polley, C.; Radlof, W.; Hauschulz, F.; Benz, C.; Sander, M.; Seitz, H.
• Is Part Of: Journal of the mechanical behavior of biomedical materials. Volume 125(2022)
• Publication Date: 2022-01
• Subjects: Gyroid scaffolds -- Electron beam melting -- Bone substitute -- Fatigue testing -- Ti6Al4V -- Porous biomaterial; Biomedical materials -- Periodicals; Biomedical materials -- Mechanical properties -- Periodicals; Biomedical materials; Biomedical materials -- Mechanical properties; Periodicals; Electronic journals; 610.28
• DOI: 10.1016/j.jmbbm.2021.104882
• Languages: English
• ISSNs: 1751-6161

Abstract

Abstract: Additive manufactured porous biomaterials based on triply periodic minimal surfaces (TPMS) are a highly discussed topic in the literature. With their unique properties in terms of open porosity, large surface area and surface curvature, they are considered to have bone mimicking properties and remarkable osteogenic potential. In this study, scaffolds of gyroid unit cells of different sizes consisting of a Ti6Al4V alloy were manufactured additively by electron beam melting (EBM). The scaffolds were analysed by micro-computed tomography (micro-CT) to determine their morphological characteristics and, subsequently, subjected to mechanical tests to investigate their quasi-static compressive properties and fatigue resistance. All scaffolds showed an average open porosity of 71–81%, with an average pore size of 0.64–1.41 mm, depending on the investigated design. The design with the smallest unit cell shows the highest quasi-elastic gradient (QEG) as well as the highest compressive offset stress and compression strength. Furthermore, the fatigue resistance of all unit cell size (UCS) variations showed promising results. In detail, the smallest unit cells achieved fatigue strength at 10 6 cycles at 45% of their compressive offset stress, which is comparatively good for additively manufactured porous biomaterials. In summary, it is demonstrated that the mechanical properties can be significantly modified by varying the unit cell size, thus enabling the scaffolds to be specifically tailored to avoid stress shielding and ensure implant safety. Together with the morphological properties of the gyroid unit cells, the fabricated scaffolds represent a promising approach for use as a bone substitute material. Graphical abstract: Image 1 Highlights: Fabrication of gyroid lattice structures with electron beam melting and varying unit cell size. X-ray micro tomography to reveal the morphometric properties and to detect imperfections. Static and fatigue compression tests performed. Scaffolds with small UCS showed the highest resistance to deformation and cyclic ratcheting during fatigue testing. All structures show the potential to avoid stress shielding.