Mechanical properties of open-cell metallic biomaterials manufactured using additive manufacturing
TL;DR: In this article, the authors present finite element (FE) models that can predict the mechanical properties of porous titanium produced using selective laser melting or selective electron beam melting using statistical models.
About: This article is published in Materials & Design.The article was published on 2013-08-01. It has received 353 citations till now. The article focuses on the topics: Selective laser melting.
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TL;DR: In this review, the current progress of two AM processes suitable for metallic orthopaedic implant applications, namely selective laser melting (SLM) and electron beam melting (EBM) are presented.
697 citations
TL;DR: A comprehensive summary of the experimental data reported on the mechanical response of Selective Laser Melting (SLM) lattice structures can be found in this paper, where the design, fabrication and performance of SLM lattice structure are reviewed and the quality of data reported to inform best-practice for future studies.
580 citations
TL;DR: In this article, the authors reviewed the recent progresses in selective laser melting of titanium alloys and their composites for biomedical applications, especially developing new titanium powder for SLM, and extended attractive progresses in the SLM of all types of titanium, composites and porous structures including Ti-24Nb-4Zr-8Sn and Ti-TiB/TiC composites with focus on the manufacture by SLM and resulting unique microstructure and properties.
Abstract: Titanium materials are ideal targets for selective laser melting (SLM), because they are expensive and difficult to machinery using traditional technologies. After briefly introducing the SLM process and processing factors involved, this paper reviews the recent progresses in SLM of titanium alloys and their composites for biomedical applications, especially developing new titanium powder for SLM. Although the current feedstock titanium powder for SLM is limited to CP-Ti, Ti–6Al–4V, and Ti–6Al–7Nb, this review extends attractive progresses in the SLM of all types of titanium, composites, and porous structures including Ti–24Nb–4Zr–8Sn and Ti–TiB/TiC composites with focus on the manufacture by SLM and resulting unique microstructure and properties (mechanical, wear/corrosion resistance properties).
524 citations
TL;DR: In this paper, the effect of build orientation selection and heat treatment on the mechanical properties of lattice structures with different geometries and their influence on mechanical properties was investigated, showing a significant decrease in mechanical strength for samples that are built diagonally and a transformation of the microstructure after a HIP (hot isostatic pressing) treatment, resulting in a lower maximum strength, but higher ductility.
Abstract: The metal additive manufacturing industry is rising and so is the interest in new lattice structures with unique mechanical properties. Many studies have already investigated lattice structures with different geometries and their influence on mechanical properties, but little is known about the effect of specific processing characteristics that are inherent to metal additive manufacturing. Therefore this study investigates the effect of two crucial steps in the manufacturing process: the build orientation selection and heat treatment. In total the microstructure and static mechanical properties of five different orientations and three heat treatment conditions were evaluated using Ti6Al4V diamond like lattice structures. The results show a significant decrease in mechanical strength for samples that are built diagonally and a transformation of the microstructure after a HIP (hot isostatic pressing) treatment, resulting in a lower maximum strength, but higher ductility. In general, horizontal struts should be avoided during manufacturing, unless the applied load after manufacturing can be properly supported by other struts. Both a stress relief heat treatment and a HIP treatment can be used in statically loaded applications, whereas a HIP treatment is believed to be beneficial for dynamically loaded applications. This study enables an appropriate selection of build orientation and heat treatment of lattice structures for different applications.
367 citations
TL;DR: Recent discoveries concerning the effects of geometrical features of porous scaffolds such as surface curvature, pore shape, and pore size on the cellular response and bone tissue regeneration process are reviewed and recommended for future research.
Abstract: The geometry of porous scaffolds that are used for bone tissue engineering and/or bone substitution has recently been shown to significantly influence the cellular response and the rate of bone tissue regeneration. Most importantly, it has been shown that the rate of tissue generation increases with curvature and is much larger on concave surfaces as compared to convex and planar surfaces. In this work, recent discoveries concerning the effects of geometrical features of porous scaffolds such as surface curvature, pore shape, and pore size on the cellular response and bone tissue regeneration process are reviewed. In addition to reviewing the recent experimental observations, we discuss the mechanisms through which geometry affects the bone tissue regeneration process. Of particular interest are the theoretical models that have been developed to explain the role of geometry in the bone tissue regeneration process. We then follow with a section on the implications of the observed phenomena for geometrical design of porous scaffolds including the application of predictive computational models in geometrical design of porous scaffolds. Moreover, some geometrical concepts in the design of porous scaffolds such as minimal surfaces and porous structures with geometrical gradients that have not been explored before are suggested for future studies. We especially focus on the porous scaffolds manufactured using additive manufacturing techniques where the geometry of the porous scaffolds could be precisely controlled. The paper concludes with a general discussion of the current state-of-the-art and recommendations for future research.
353 citations
Cites background from "Mechanical properties of open-cell ..."
...shapes such as cubic unit cells to more complex shapes such as rhombic dodecahedron and diamond-type unit cell [45, 46], and even advanced geometrical shapes such as minimal...
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TL;DR: In this paper, it is shown that to answer several questions of physical or engineering interest, it is necessary to know only the relatively simple elastic field inside the ellipsoid.
Abstract: It is supposed that a region within an isotropic elastic solid undergoes a spontaneous change of form which, if the surrounding material were absent, would be some prescribed homogeneous deformation. Because of the presence of the surrounding material stresses will be present both inside and outside the region. The resulting elastic field may be found very simply with the help of a sequence of imaginary cutting, straining and welding operations. In particular, if the region is an ellipsoid the strain inside it is uniform and may be expressed in terms of tabulated elliptic integrals. In this case a further problem may be solved. An ellipsoidal region in an infinite medium has elastic constants different from those of the rest of the material; how does the presence of this inhomogeneity disturb an applied stress-field uniform at large distances? It is shown that to answer several questions of physical or engineering interest it is necessary to know only the relatively simple elastic field inside the ellipsoid.
11,784 citations
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...of ellipsoidal inclusions [14–17] was used....
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01 Aug 1988TL;DR: The linear elasticity of anisotropic cellular solids is studied in this article. But the authors focus on the design of sandwich panels with foam cores and do not consider the properties of the materials.
Abstract: 1. Introduction 2. The structure of cellular solids 3. Material properties 4. The mechanics of honeycombs 5. The mechanics of foams: basic results 6. The mechanics of foams refinements 7. Thermal, electrical and acoustic properties of foams 8. Energy absorption in cellular materials 9. The design of sandwich panels with foam cores 10. Wood 11. Cancellous bone 12. Cork 13. Sources, suppliers and property data Appendix: the linear-elasticity of anisotropic cellular solids.
8,946 citations
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...open cellular structures [12]....
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TL;DR: In this paper, a simple theoretical model is developed to predict residual stress distributions in selective laser sintering (SLS) and selective laser melting (SLM), aiming at a better understanding of this phenomenon.
Abstract: Purpose – This paper presents an investigation into residual stresses in selective laser sintering (SLS) and selective laser melting (SLM), aiming at a better understanding of this phenomenon.Design/methodology/approach – First, the origin of residual stresses is explored and a simple theoretical model is developed to predict residual stress distributions. Next, experimental methods are used to measure the residual stress profiles in a set of test samples produced with different process parameters.Findings – Residual stresses are found to be very large in SLM parts. In general, the residual stress profile consists of two zones of large tensile stresses at the top and bottom of the part, and a large zone of intermediate compressive stress in between. The most important parameters determining the magnitude and shape of the residual stress profiles are the material properties, the sample and substrate height, the laser scanning strategy and the heating conditions.Research limitations/implications – All exper...
1,415 citations
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...For example, the residual stress caused by high temperature laser melting process are found to be very large [24] and may lower the mechanical properties of the porous material....
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TL;DR: In this paper, a 3D asymmetric fracture locus, in the space of equivalent fracture strain, stress triaxiality and the Lode angle parameter, is proposed.
1,351 citations
TL;DR: Over the years, a variety of fabrication processes have been developed, resulting in porous implant substrates that can address unresolved clinical problems, and all known methods for fabricating such porous metallic scaffolds are summarized.
1,292 citations
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...Several manufacturing techniques exist for production of porous metals [5] including the space holder technology [6] and additive manufacturing techniques [7]....
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