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. 2018 Mar 3;11(3):374.
doi: 10.3390/ma11030374.

Mechanical Properties of Optimized Diamond Lattice Structure for Bone Scaffolds Fabricated via Selective Laser Melting

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Free PMC article

Mechanical Properties of Optimized Diamond Lattice Structure for Bone Scaffolds Fabricated via Selective Laser Melting

Fei Liu et al. Materials (Basel). .
Free PMC article

Abstract

Developments in selective laser melting (SLM) have enabled the fabrication of periodic cellular lattice structures characterized by suitable properties matching the bone tissue well and by fluid permeability from interconnected structures. These multifunctional performances are significantly affected by cell topology and constitutive properties of applied materials. In this respect, a diamond unit cell was designed in particular volume fractions corresponding to the host bone tissue and optimized with a smooth surface at nodes leading to fewer stress concentrations. There were 33 porous titanium samples with different volume fractions, from 1.28 to 18.6%, manufactured using SLM. All of them were performed under compressive load to determine the deformation and failure mechanisms, accompanied by an in-situ approach using digital image correlation (DIC) to reveal stress-strain evolution. The results showed that lattice structures manufactured by SLM exhibited comparable properties to those of trabecular bone, avoiding the effects of stress-shielding and increasing longevity of implants. The curvature of optimized surface can play a role in regulating the relationship between density and mechanical properties. Owing to the release of stress concentration from optimized surface, the failure mechanism of porous titanium has been changed from the pattern of bottom-up collapse by layer (or cell row) to that of the diagonal (45°) shear band, resulting in the significant enhancement of the structural strength.

Keywords: bone scaffolds; compressive deformation behavior; laser powder bed fusion; lattice structure; selective laser melting; structure optimization.

Conflict of interest statement

The authors declare no conflict of interest.

Figures

Figure 1
Figure 1
The experimental conditions: (a) sample 0600 without optimization, (b) sample 0616 with surface optimization at nodes (where ‘06’ denotes D = 0.6 mm, ‘16’ denotes R = 1.6 mm), (c) a node without optimization, (d) one of the unit cells used in the diamond-type 3 × 3 × 3 cellular structures, (e) a node with optimized surface.
Figure 2
Figure 2
Value of volume fraction determined by rod diameter and optimized-radius.
Figure 3
Figure 3
SEM micrographs of the Ti6Al4V powder, (a) ×500 and (b) ×2000.
Figure 4
Figure 4
The formed samples by selective laser melting with a dimension of 16.5 × 16.5 × 16.5 mm3 (where ‘10′ denotes D = 1.0 mm, ‘16′ denotes R = 1.6 mm, and other numbers (for example, ‘1008′) are similar).
Figure 5
Figure 5
Comparison between CAD models and as-built samples.
Figure 6
Figure 6
(ad) The stress–strain curves; (eh) the corresponding relative ultimate stress σ* and relative modulus E*.
Figure 7
Figure 7
Values of C1 and C2 with the increase of optimized-radius.
Figure 8
Figure 8
Mechanical properties of the diamond structures with different optimized-radius: (a) Elastic modulus; (b) ultimate stress; (c) the relationship between elastic modulus and compression strength.
Figure 9
Figure 9
Compressive stress–strain curve of 0600, 0610 and 0616 samples.
Figure 10
Figure 10
SEM morphologies of fracture surface: (ac) tensile yield at node with ductile dimpling for sample 0600, (dg) shear rupture at rod for sample 0616.

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References

    1. Evans A.G., Hutchinson J.W., Fleck N., Ashby M.F., Wadley H.N.G. The topological design of multifunctional cellular metals. Prog. Mater. Sci. 2001;46:309–327. doi: 10.1016/S0079-6425(00)00016-5. - DOI
    1. Olivares A.L., Marsal È., Planell J.A., Lacroix D. Finite element study of scaffold architecture design and culture conditions for tissue engineering. Biomaterials. 2009;30:6142–6149. doi: 10.1016/j.biomaterials.2009.07.041. - DOI - PubMed
    1. Wang X., Xu S., Zhou S., Xu W., Leary M., Choong P., Qian M., Brandt M., Xie Y.M. Topological design and additive manufacturing of porous metals for bone scaffolds and orthopaedic implants: A review. Biomaterials. 2016;83:127–141. doi: 10.1016/j.biomaterials.2016.01.012. - DOI - PubMed
    1. Ahmadi S.M., Campoli G., Amin Yavari S., Sajadi B., Wauthle R., Schrooten J., Weinans H., Zadpoor A.A. Mechanical behavior of regular open-cell porous biomaterials made of diamond lattice unit cells. J. Mech. Behav. Biomed. 2014;34:106–115. doi: 10.1016/j.jmbbm.2014.02.003. - DOI - PubMed
    1. Kadkhodapour J., Montazerian H., Darabi A.C., Anaraki A.P., Ahmadi S.M., Zadpoor A.A., Schmauder S. Failure mechanisms of additively manufactured porous biomaterials: Effects of porosity and type of unit cell. J. Mech. Behav. Biomed. 2015;50:180–191. doi: 10.1016/j.jmbbm.2015.06.012. - DOI - PubMed
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