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Additive manufacturing has been used to develop a variety of scaffold designs for clinical and industrial applications. Mechanical properties (i.e., compression, tension, bending, and torsion response) of these scaffolds are significantly important for load-bearing orthopaedic implants. In this study, we designed and additively manufactured porous metallic biomaterials based on two different types of triply periodic minimal surface structures (i.e., gyroid and diamond) that mimic the mechanical properties of bone, such as porosity, stiffness, and strength. Physical and mechanical properties, including compressive, tensile, bending, and torsional stiffness and strength of the developed scaffolds, were then characterised experimentally and numerically using finite element method. Sheet thickness was constant at 300 μm, and the unit cell size was varied to generate different pore sizes and porosities. Gyroid scaffolds had a pore size in the range of 600–1200 μm and a porosity in the range of 54–72%, respectively. Corresponding values for the diamond were 900–1500 μm and 56–70%. Both structure types were validated experimentally, and a wide range of mechanical properties (including stiffness and yield strength) were predicted using the finite element method. The stiffness and strength of both structures are comparable to that of cortical bone, hence reducing the risks of scaffold failure. The results demonstrate that the developed scaffolds mimic the physical and mechanical properties of cortical bone and can be suitable for bone replacement and orthopaedic implants. However, an optimal design should be chosen based on specific performance requirements.
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Design and additive manufacturing of porous titanium scaffolds for optimum cell viability in bone tissue engineering
Pore size, external shape, and internal complexity of additively manufactured porous titanium scaffolds are three primary determinants of cell viability and structural strength of scaffolds in bone tissue engineering. To obtain an optimal design with the combination of all three determinants, four scaffolds each with a unique topology (external geometry and internal structure) were designed and varied the pore sizes of each scaffold 3 times. For each topology, scaffolds with pore sizes of 300, 400, and 500 µm were designed. All designed scaffolds were additively manufactured in material Ti6Al4V by the direct metal laser melting machine. Compression test was conducted on the scaffolds to assure meeting minimum compressive strength of human bone. The effects of pore size and topology on the cell viability of the scaffolds were analyzed. The 12 scaffolds were ultrasonically cleaned and seeded with NIH3T3 cells. Each scaffold was seeded with 1 million cells. After 32 days of culturing, the cells were fixed for their three-dimensional architecture preservation and to obtain scanning electron microscope images.
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- Award ID(s):
- 1712391
- PAR ID:
- 10186231
- Date Published:
- Journal Name:
- Proceedings of the Institution of Mechanical Engineers, Part B: Journal of Engineering Manufacture
- ISSN:
- 0954-4054
- Page Range / eLocation ID:
- 095440542093756
- Format(s):
- Medium: X
- Sponsoring Org:
- National Science Foundation
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Accepted Manuscript1.0
- Journal Article:
- https://doi.org/10.1177/0954405420937565
