finite element analysis of human femur n.
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FINITE ELEMENT ANALYSIS OF HUMAN FEMUR
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  1. FINITE ELEMENT ANALYSIS OF HUMAN FEMUR H. A.KHAWAJA (PhD Student, Dept. of Engineering) A. NAIK (PhD Student, Dept. of Material Sciences) K.PARVEZ (Professor; Research Centre for Modelling & Simulation) 4TH INT. CONFERENCEOF MULTIPHYICS, LILLE, FRANCE, 9-11DEC 09

  2. 2 H. A.KHAWAJAMULTIPHYSICS 2009, LILLE, FRANCE, 9-11 DEC 09 POINTSFOR DISCUSSION • INTRODUCTION • FEMUR CAD DEVELOPMENT • Laser 3-D Scanning • CAD Model • Marrow Cavity (Approx.) • FINITE ELEMENT ANALYSIS • Finite Element Modelling • Material Properties and Assumptions • Loading and Boundary Conditions • Finite Element Analysis Results • SUMMARY & CONCLUSION • REFERNCES • ACKNOWLEDGEMENTS

  3. 3 H. A.KHAWAJAMULTIPHYSICS 2009, LILLE, FRANCE, 9-11 DEC 09 INTRODUCTION • Largest Human Bone • Single Support Member • Less Flexible (Stiff) • Anisotropic Material FEMUR • This work addresses: • Load Bearing limit of Femur • Natural Safety Factor • Results will aid in deciding substitute material for bone

  4. 4 H. A.KHAWAJAMULTIPHYSICS 2009, LILLE, FRANCE, 9-11 DEC 09 FEMUR CAD DEVELOPMENT • Laser 3-D Scanning: COORDINATES CLOUD OBJECT LASER SCAN ROTATION

  5. 5 H. A.KHAWAJAMULTIPHYSICS 2009, LILLE, FRANCE, 9-11 DEC 09 FEMUR CAD DEVELOPMENT • CAD Model: • Marrow Cavity is developed based on approximation

  6. 6 H. A.KHAWAJAMULTIPHYSICS 2009, LILLE, FRANCE, 9-11 DEC 09 FINITE ELEMENT MODELLING • Finite Element Mesh: • Tetrahedral 20-noded 186 structural solid element has been used • Mesh sensitivity analysis is carried out to ensure the quality of results • Mesh has been refined in the regions of high Gradients

  7. 7 H. A.KHAWAJAMULTIPHYSICS 2009, LILLE, FRANCE, 9-11 DEC 09 FINITE ELEMENT MODELLING • Material Properties & Assumptions: • Originally Bone material is anisotropic but assumed to be isotropic because complete femur was taken for analysis; a piece of bone could be solved for anisotropic solution but not the complete bone. • The bone Young’s modulus varies between 10 to 20 GPa. The Poisson’s ratio is about 0.3 *. “For linear static analysis stresses doesn’t depend on modulus of elasticity” • Physiological conditions has been ignored for time being; e.g. muscle stresses. y x z *BAOHUA, J., HUAJIN, GAO., (2004). Journal of Mechanics and Physics of Solids, 52, 1963-1990.

  8. 8 H. A.KHAWAJAMULTIPHYSICS 2009, LILLE, FRANCE, 9-11 DEC 09 FINITE ELEMENT MODELLING • Loading & Boundary Conditions: • Axial Load • Bending Load • Based on its position w.r.t. Its orientation • Load is varied until failure

  9. 9 H. A.KHAWAJAMULTIPHYSICS 2009, LILLE, FRANCE, 9-11 DEC 09 FINITE ELEMENT MODELLING • Finite Element Results (Compression): • Displacement Contour Plot 1 Units = 1 metres

  10. 10 H. A.KHAWAJAMULTIPHYSICS 2009, LILLE, FRANCE, 9-11 DEC 09 FINITE ELEMENT MODELLING • Finite Element Results (Compression): • Von-Mises Stress Contour Plot 1 Units = 1 Pascal Max. Stress regions coincides under axial and bending load

  11. 11 H. A.KHAWAJAMULTIPHYSICS 2009, LILLE, FRANCE, 9-11 DEC 09 FLUIDIZED BED FINITE ELEMENT MODELLING • Finite Element Results (Based on 70 Kg Human Weight): • 69 Kg is limit load under bending load and 414 Kg is limit load under axial load. • *Failure limit is 100 MPa(BAOHUA, J., HUAJIN, GAO., (2004). Journal of Mechanics and Physics of Solids, 52, 1963-1990.)

  12. 12 H. A.KHAWAJAMULTIPHYSICS 2009, LILLE, FRANCE, 9-11 DEC 09 SUMMARY & CONCLUSION • Summary: • 3-D CAD Model has been developed via Laser Scanning • Approximations have been applied on material and model • Finite Element Analysis has been conducted • Results are evaluated • Conclusion: • Natural Margin of Safety under 35 Kg Design Load (70Kg average Human) of compression is 9.74. • Natural Margin of Safety under 35 Kg Design Load (70Kg average Human) of bending is 0.952. • Human Femur is designed to bear 10 times more load compared to load at normal conditions. It has also been found out Femur resistance to fracture under compression is approx. 5 times to the bending.

  13. 13 H. A.KHAWAJAMULTIPHYSICS 2009, LILLE, FRANCE, 9-11 DEC 09 FUTURE WORK • Evaluated results are the indicative of the mechanical properties of substitute material for bones. • Physiological conditions may be involved to increase the accuracy of results. • Whole human bone structure may be solved via FEM under the availability of computational resources.

  14. 14 H. A.KHAWAJAMULTIPHYSICS 2009, LILLE, FRANCE, 9-11 DEC 09 REFERENCES

  15. 15 H. A.KHAWAJAMULTIPHYSICS 2009, LILLE, FRANCE, 9-11 DEC 09 ACKNOWLEDGEMENTS • Institute of Space Technology (IST) – Pakistan • Cambridge Commonwealth Trust – Cambridge, UK • Research Centre for Modelling & Simulation, National University of Sciences & Technology (NUST) - Pakistan

  16. THANK YOU CONTACT HASSAN KHAWAJA Email: hak23@cam.ac.uk Webpage: http://hassanabbaskhawaja.blogspot.com