A finite element study of invariant-based orthotropic constitutive equations in the context of myocardial material parameter estimation |
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Authors: | H Schmid W Wang PJ Hunter MP Nash |
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Institution: | 1. Department of Continuum Mechanics , RWTH Aachen University , Eilfschornsteinstr. 18, 56062, Aachen, Germany schmid@km.rwth-aachen.de;3. Auckland Bioengineering Institute, University of Auckland , Private Bag, 92019, Auckland, New Zealand |
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Abstract: | A previous study investigated a number of invariant-based orthotropic and transversely isotropic constitutive equations for their suitability to fit three-dimensional simple shear mechanics data of passive myocardial tissue. The study was based on the assumption of a homogeneous deformation. Here, we extend the previous study by performing an inverse finite element material parameter estimation. This ensures a more realistic deformation state and material parameter estimates. The constitutive relations were compared on the basis of (i) ‘goodness of fit’: how well they fit a set of six shear deformation tests and (ii) ‘variability’: how well determined the material parameters are over the range of experiments. These criteria were utilised to discuss the advantages and disadvantages of the constitutive relations. It was found that a specific form of the polyconvex type as well as the exponential Fung-type equations were most suitable for modelling the orthotropic behaviour of myocardium under simple shear. |
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Keywords: | inverse parameter estimation myocardium orthotropic transversely isotropic polyconvexity |
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