Document Type : Original Article
Authors
1
Faculty of Mechanical Engineering, University of Tehran, Tehran, Iran
2
Department of Biomechanics, Faculty of Mechanical Engineering, University of Tehran, Tehran, Iran
3
professor, Faculty of Mechanical Engineering, University of Tehran,, Tehran,, Iran Member, of Center for Advanced Orthopedic Studies, Harvard Medical School, Boston,, Massachusetts,, USA
Abstract
The natural frequencies and mode shapes of bone are widely used in the diagnosis of bone fracture healing, bone remodeling, osteoporosis diagnosis, and implant-bone interaction. These characteristics can be estimated using numerical analysis and finite element modeling and measured and validated by modal testing of laboratory samples. Bone heterogeneity in finite element models affects its natural frequency. In this research, the effect of bone heterogeneity and density-elasticity relationships on the natural frequency of bone and the accuracy of their estimation have been investigated. A cow tibia bone was prepared and subjected to modal test. The experimental results of the modal test were compared with the results of the 3D finite element model created from the bone CT scan images. Inhomogeneity based on the proposed density-elasticity relationships was applied element by element (continuous) and regionally based on a tolerance (discrete) in the model. Comparing the results of heterogeneous models with experimental results shows that there is very little difference between the natural frequencies of discrete and continuous heterogeneous models. So, for the first five frequencies, a discrete heterogeneous model with 20 regions can predict the natural frequencies with an error of less than 2% with less cost and shorter time.
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