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Keywords: trabecular bone, nanoindentation, micromechanical testing, optical strain measurement, constitutive models, finite element modelling.

Summary

This paper presents a comparison between the mechanical properties of a single human trabeculae obtained by micromechanical testing and those assessed by nanoindentation. A compact uniaxial tension-compression device has been developed for this purpose enabling precise positioning, alignment and loading of a single trabecula as well as reliable force measurement. The strains at the surface of the sample are measured optically using a high-resolution CCD camera. The strain field is evaluated using an image correlation technique applied to the whole surface of the loaded sample. Local micromechanical properties were assessed using nanoindentation. Flat polished cross sections of the trabecular bone were covered with series of imprints in the submicron depth range.

From the nanoindentation curves obtained material parameters for the elasto-plastic constitutive model with isotropic hardening are identified for a finite element simulation of the indentation process. A rotationally symmetric finite element model is created with a four-parameter elasto-plastic material model used for the trabecular bone tissue. The unknown parameters are identified in a large set of parametric studies in which the response of the model is best-fitted to the experimental curve.

Validation of the material model obtained from nanoindentation is presented in a simulation of the tensile test of a single trabecula. For each sample, the stress-strain curve is developed from the finite element simulation and compared to an experimentally determined one. The results of this study provide useful information about intra-trabecular variation of mechanical properties and can be useful in detailed finite element simulations of healthy and osteoporotic trabecular structures subject to mechanical loading where the overall response of larger models is required.

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Front Page Browse CCP CSETS CTR IJRT Other Authors Search Purchase Guide FAQ Contact us	Civil-Comp Proceedings ISSN 1759-3433 CCP: 96 PROCEEDINGS OF THE THIRTEENTH INTERNATIONAL CONFERENCE ON CIVIL, STRUCTURAL AND ENVIRONMENTAL ENGINEERING COMPUTING Edited by: B.H.V. Topping and Y. Tsompanakis Paper 238 Simulation of the Mechanical Behaviour of a Single Human Trabecula assessed with a Micromechanical Test and Nanoindentation O. Jiroušek¹, D. Kytýr^1,2, J. Kunecký¹, P. Zlámal^1,2, T. Doktor^1,2 and J. Nemecek³ ¹Institute of Theoretical and Applied Mechanics AS CR, v.v.i, Czech Republic ²Faculty of Transportation Sciences, ³Faculty of Civil Engineering, CTU in Prague, Czech Republic doi:10.4203/ccp.96.238 purchase the full-text of this paper Full Bibliographic Reference for this paper , "Simulation of the Mechanical Behaviour of a Single Human Trabecula assessed with a Micromechanical Test and Nanoindentation", in B.H.V. Topping, Y. Tsompanakis, (Editors), "Proceedings of the Thirteenth International Conference on Civil, Structural and Environmental Engineering Computing", Civil-Comp Press, Stirlingshire, UK, Paper 238, 2011. doi:10.4203/ccp.96.238 Keywords: trabecular bone, nanoindentation, micromechanical testing, optical strain measurement, constitutive models, finite element modelling. Summary This paper presents a comparison between the mechanical properties of a single human trabeculae obtained by micromechanical testing and those assessed by nanoindentation. A compact uniaxial tension-compression device has been developed for this purpose enabling precise positioning, alignment and loading of a single trabecula as well as reliable force measurement. The strains at the surface of the sample are measured optically using a high-resolution CCD camera. The strain field is evaluated using an image correlation technique applied to the whole surface of the loaded sample. Local micromechanical properties were assessed using nanoindentation. Flat polished cross sections of the trabecular bone were covered with series of imprints in the submicron depth range. From the nanoindentation curves obtained material parameters for the elasto-plastic constitutive model with isotropic hardening are identified for a finite element simulation of the indentation process. A rotationally symmetric finite element model is created with a four-parameter elasto-plastic material model used for the trabecular bone tissue. The unknown parameters are identified in a large set of parametric studies in which the response of the model is best-fitted to the experimental curve. Validation of the material model obtained from nanoindentation is presented in a simulation of the tensile test of a single trabecula. For each sample, the stress-strain curve is developed from the finite element simulation and compared to an experimentally determined one. The results of this study provide useful information about intra-trabecular variation of mechanical properties and can be useful in detailed finite element simulations of healthy and osteoporotic trabecular structures subject to mechanical loading where the overall response of larger models is required. purchase the full-text of this paper (price £20) go to the previous paper go to the next paper return to the table of contents return to the book description purchase this book (price £130 +P&P)
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