Journal Article

PreJuSER-10735

http://join2-wiki.gsi.de/foswiki/pub/Main/Artwork/join2_logo100x88.png Characterization of the deformation behavior of intermediate porosity interconnected Ti foams using micro-computed tomography and direct finite element modelling

Singh, R. ; Lee, P. D. ; Lindley, T. C. ; Hellmich, C. ; Bram, M.FZJ* ; Imwinkelried, T. ; Dashwood, R. J.

2010
Wiley VCH Berlin

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Please use a persistent id in citations: doi:10.1016/j.actbio.2009.11.032

Abstract: Under load-bearing conditions metal-based foam scaffolds are currently the preferred choice as bone/cartilage implants. In this study X-ray micro-computed tomography was used to discretize the three-dimensional structure of a commercial titanium foam used in spinal fusion devices. Direct finite element modeling, continuum micromechanics and analytical models of the foam were employed to characterize the elasto-plastic deformation behavior. These results were validated against experimental measurements, including ultrasound and monotonic and interrupted compression testing. Interrupted compression tests demonstrated localized collapse of pores unfavorably oriented with respect to the loading direction at many isolated locations, unlike the Ashby model, in which pores collapse row by row. A principal component analysis technique was developed to quantify the pore anisotropy which was then related to the yield stress anisotropy, indicating which isolated pores will collapse first. The Gibson-Ashby model was extended to incorporate this anisotropy by considering an orthorhombic, rather than a tetragonal, unit cell. It is worth noting that the natural bone is highly anisotropic and there is a need to develop and characterize anisotropic implants that mimic bone characteristics.

Keyword(s): Biocompatible Materials: chemistry (MeSH) ; Computer Simulation (MeSH) ; Elastic Modulus (MeSH) ; Finite Element Analysis (MeSH) ; Gases: chemistry (MeSH) ; Hardness (MeSH) ; Materials Testing (MeSH) ; Models, Chemical (MeSH) ; Stress, Mechanical (MeSH) ; Titanium: chemistry (MeSH) ; Tomography, X-Ray Computed: methods (MeSH) ; Biocompatible Materials ; Gases ; Titanium ; J ; Titanium foam (auto) ; Porous materials (auto) ; Finite element modeling (auto) ; X-ray micro-tomography (auto) ; Biomaterials (auto)

Note: The authors acknowledge the useful discussions and assistance of R.C. Atwood and R. Hamilton with the mu CT studies. Andreas Fritsch (Technische Universitat Wien) is gratefully acknowledged for his assistance with the continuum micromechanics modeling. We thank the European Synchrotron Radiation Facility for the provision of synchrotron radiation facilities and especially the team of beam line ID19. We would also like to thank the EPSRC (GR/T26344) for support for the computational facilities and one of the authors (R.S.) gratefully acknowledges financial support from the EC under a Marie Curie Fellowship Grant.

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Contributing Institute(s):

1. Werkstoffsynthese und Herstellungsverfahren (IEF-1)

Research Program(s):

1. Rationelle Energieumwandlung (P12)

Appears in the scientific report 2010

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