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Finite Element Modeling and Damage Evaluation of Annulus Fibrosus

Momeni Shahraki, Narjes
http://rave.ohiolink.edu/etdc/view?acc_num=toledo1413371575

Abstract Details

2014, Master of Science, University of Toledo, Mechanical Engineering.
Besides the biology, stresses and strains within the tissue greatly influence the location of damage initiation, damage evaluation, and mode of failure in an intervertebral disc. Finite element models of a functional spinal unit (FSU) that incorporate reasonably accurate geometry and appropriate material properties are suitable to investigate such issues. There are several material models for the annulus, but their abilities to predict relevant clinically observed damage in the anisotropic annulus fibrosus are not clear. As a result, a finite element study using a three-dimensional model of a ligamentous FSU is undertaken in this study. Appropriate material properties of the ligaments, disc, nucleus, facet cartilage, and vertebral bodies were assigned from the literature. A hyperelastic anisotropic material model for the annulus with two different sets of material constants, experimentally determined using uniaxial and biaxial loading conditions, were incorporated in this model. The first aim of this study was to highlight the biomechanical differences (e.g., intradiscal pressure, motion, forces, stresses and strains, etc.) due to the dissimilarity between the two sets of material properties (uniaxial and biaxial). Based on the analyses, the biaxial constants simulations resulted in better agreements with the in-vitro and in-vivo data, and thus are more suitable for damage analysis and failure prediction of the annulus under complex multi-axial loading conditions. Observing initiation of internal damage in the annulus fibrosus during cadaveric experiments or via imaging in clinical scenarios is difficult and finite element analysis provides a valuable tool for this purpose. Therefore, the second aim of this study was to use the hyperelastic anisotropic material model in conjunction with biaxial properties mentioned for evaluating damage under a variety of loading conditions. The loading conditions considered include compression, flexion, extension, and their combinations. Maximum normal stress (MNS) and Tsai-Wu criteria were used to evaluate the damage. Strength anisotropy and asymmetry were considered in both criteria. According to the results of this part of the study, the damage predictions based on Tsai-Wu criterion were in better agreement with available experimental studies and clinical observations.
Ali Fatemi (Committee Co-Chair)
Vijay Goel (Committee Co-Chair)
Anand Agarwal (Committee Member)
106 p.
Biomedical Engineering; Mechanical Engineering

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Citations

  • Momeni Shahraki, N. (2014). Finite Element Modeling and Damage Evaluation of Annulus Fibrosus [Master's thesis, University of Toledo]. OhioLINK Electronic Theses and Dissertations Center. http://rave.ohiolink.edu/etdc/view?acc_num=toledo1413371575

    APA Style (7th edition)

  • Momeni Shahraki, Narjes. Finite Element Modeling and Damage Evaluation of Annulus Fibrosus . 2014. University of Toledo, Master's thesis. OhioLINK Electronic Theses and Dissertations Center, http://rave.ohiolink.edu/etdc/view?acc_num=toledo1413371575.

    MLA Style (8th edition)

  • Momeni Shahraki, Narjes. "Finite Element Modeling and Damage Evaluation of Annulus Fibrosus ." Master's thesis, University of Toledo, 2014. http://rave.ohiolink.edu/etdc/view?acc_num=toledo1413371575

    Chicago Manual of Style (17th edition)

toledo1413371575
1,126
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This open access ETD is published by University of Toledo and OhioLINK.