A constitutive model for fibrous tissues considering collagen fiber crimp |
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Authors: | F. Cacho,P.J. Elbischger,M. Doblaré |
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Affiliation: | a Institute for Structural Analysis, Computational Biomechanics, Graz University of Technology, Austria b Group of Structural Mechanics and Materials Modeling, Aragon Institute of Engineering Research (I3A), University of Zaragoza, Spain c Medical Information Technology, Carinthia Tech Institute, University of Applied Sciences, Klagenfurt, Austria d Department of Solid Mechanics, School of Engineering Sciences, Royal Institute of Technology (KTH), Stockholm, Sweden e Institute for Biomechanics, Graz University of Technology, Austria |
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Abstract: | A micromechanically based constitutive model for fibrous tissues is presented. The model considers the randomly crimped morphology of individual collagen fibers, a morphology typically seen in photomicrographs of tissue samples. It describes the relationship between the fiber endpoints and its arc-length in terms of a measurable quantity, which can be estimated from image data. The collective mechanical behavior of collagen fibers is presented in terms of an explicit expression for the strain-energy function, where a fiber-specific random variable is approximated by a Beta distribution. The model-related stress and elasticity tensors are provided. Two representative numerical examples are analyzed with the aim of demonstrating the peculiar mechanism of the constitutive model and quantifying the effect of parameter changes on the mechanical response. In particular, a fibrous tissue, assumed to be (nearly) incompressible, is subject to a uniaxial extension along the fiber direction, and, separately, to pure shear. It is shown that the fiber crimp model can reproduce several of the expected characteristics of fibrous tissues. |
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Keywords: | Collagen fiber Constitutive model Fiber crimp Micromechanics Statistical distribution |
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