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The study describes the recoverable strain in Ti-24Nb-4Zr-8Sn (wt.%) alloy with cellular structure having rhombic dodecahedron and topology-optimised unit cell fabricated by electron beam melting. At a certain cyclic strain, the recoverable strain in rhombic dodecahedron structure was greater in comparison to topology-optimised structure because of different stress distribution on struts. The cellular structure of Ti-24Nb-4Zr-8Sn alloy with rhombic dodecahedron unit cell had larger recoverable strain in comparison to Ti-6Al-4V cellular structure. This behaviour is attributed to higher strength to modulus ratio (σ/E) and superelasticity of Ti-24Nb-4Zr-8Sn alloy. [ABSTRACT FROM AUTHOR]

Additive manufacturing technique is a promising approach for fabricating cellular bone substitutes such as trabecular and cortical bones because of the ability to adjust process parameters to fabricate different shapes and inner structures. Considering the long term safe application in human body, the metallic cellular implants are expected to exhibit superior fatigue property. The objective of the study was to study the influence of cell shape on the compressive fatigue behavior of Ti-6Al-4V mesh arrays fabricated by electron beam melting. The results indicated that the underlying fatigue mechanism for the three kinds of meshes (cubic, G7 and rhombic dodecahedron) is the interaction of cyclic ratcheting and fatigue crack growth on the struts, which is closely related to cumulative effect of buckling and bending deformation of the strut. By increasing the buckling deformation on the struts through cell shape design, the cyclic ratcheting rate of the meshes during cyclic deformation was decreased and accordingly, the compressive fatigue strength was increased. With increasing bending deformation of struts, fatigue crack growth in struts contributed more to the fatigue damage of meshes. Rough surface and pores contained in the struts significantly deteriorated the compressive fatigue strength of the struts. By optimizing the buckling and bending deformation through cell shape design, Ti-6Al-4V alloy cellular solids with high fatigue strength and low modulus can be fabricated by the EBM technique. [ABSTRACT FROM AUTHOR]

In recent years, mesh structures have attracted significant interest for structural and functional applications. However, the mechanical strength and energy absorption ability of uniform mesh structured materials degrade with density. To address this challenge, we propose the concept of functionally graded mesh structures. The objective of the proposed research is to fundamentally understand the compressive behavior of graded mesh structures. The compression-compression fatigue behavior of functionally graded Ti–6Al–4V mesh structure under identical bulk stress condition is studied here. During cyclic deformation, it was observed that the local stress distribution in the struts was not uniform because of inhomogeneous mechanical properties of the constituents. Fatigue cracks first initiated in the lowest strength constituent, and then propagated until structural failure occurred. However, no obvious damage was observed in other constituents during the entire process. In contrast with iso-strain state, the fatigue life of graded structure is mainly determined by the constituent with the lowest strength. [ABSTRACT FROM AUTHOR]