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Materials (Basel). 2018 Mar 3;11(3). pii: E374. doi: 10.3390/ma11030374.

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

Author information

1
State Key Laboratory of Mechanical Transmission, Chongqing University, Chongqing 400044, China. liufei29@cqu.edu.cn.
2
State Key Laboratory of Mechanical Transmission, Chongqing University, Chongqing 400044, China. zhangzw@cqu.edu.cn.
3
College of Engineering, Mathematics and Physical Sciences, University of Exeter, North Park Road, Exeter EX4 4QF, UK. zhangzw@cqu.edu.cn.
4
State Key Laboratory of Mechanical Transmission, Chongqing University, Chongqing 400044, China. pengzhang@cqu.edu.cn.
5
State Key Laboratory of Mechanical Transmission, Chongqing University, Chongqing 400044, China. zhaomiaocqu@gmail.com.
6
State Key Laboratory of Mechanical Transmission, Chongqing University, Chongqing 400044, China. salman6537@gmail.com.

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

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