Modelling of transversely isotropic nonlinear incompressible soft tissues using spectral invariants

In isotropic elasticity, numerous strain energy functions with different types of invariants are developed to serve certain purposes. This wealth of functions has partly contributed to the knowledge of the mechanical behaviour of isotropic elastic solids. In general, soft tissues are not isotropic b...

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Main Author: Ayem, Mahad
Format: Thesis
Language:English
Published: 2017
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Online Access:http://eprints.utm.my/id/eprint/79356/1/MahadAyemPFS2017.pdf
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spelling my-utm-ep.793562018-10-14T08:44:51Z Modelling of transversely isotropic nonlinear incompressible soft tissues using spectral invariants 2017 Ayem, Mahad QA Mathematics In isotropic elasticity, numerous strain energy functions with different types of invariants are developed to serve certain purposes. This wealth of functions has partly contributed to the knowledge of the mechanical behaviour of isotropic elastic solids. In general, soft tissues are not isotropic but can be modelled as transversely isotropic solid. The knowledge of the mechanical behaviour of transversely isotropic elastic solids is not as profound as isotropic solid. Hence, the need to develop accurate strain energy functions to understand the mechanical behaviour of transversely isotropic soft tissues. In isotropic elasticity, phenomenological strain energy functions with principal stretches have certain attractive features from both the mathematical and physical viewpoints. These forms of strain energy have been widely and successfully used in prediction of elastic deformations. This research is an extension from classical invariants of isotropic models to characterize transversely isotropic soft tissues with spectral invariants. In order to obtain a specific form of the strain energy function from an experiment, it is convenient to have explicit and analytic expressions for the derivatives of the strain energy function with respect to its invariants. Three of the invariants are the principal extension ratios and the other two are the cosines of the angles between the principal directions of the right stretch tensor and the material preferred direction. These direct physical interpretations of the invariants shows that the model has an experimental advantage where a triaxial test can vary a single invariant while keeping the remaining invariants fixed. The symmetrical and orthogonal properties developed here are similar to that possessed by a strain energy function of an isotropic elastic solid written in terms of principal stretches. A specific constitutive model was applied to biological soft tissues and the model compares well with existing experimental data. 2017 Thesis http://eprints.utm.my/id/eprint/79356/ http://eprints.utm.my/id/eprint/79356/1/MahadAyemPFS2017.pdf application/pdf en public phd doctoral Universiti Teknologi Malaysia, Faculty of Science Faculty of Science
institution Universiti Teknologi Malaysia
collection UTM Institutional Repository
language English
topic QA Mathematics
spellingShingle QA Mathematics
Ayem, Mahad
Modelling of transversely isotropic nonlinear incompressible soft tissues using spectral invariants
description In isotropic elasticity, numerous strain energy functions with different types of invariants are developed to serve certain purposes. This wealth of functions has partly contributed to the knowledge of the mechanical behaviour of isotropic elastic solids. In general, soft tissues are not isotropic but can be modelled as transversely isotropic solid. The knowledge of the mechanical behaviour of transversely isotropic elastic solids is not as profound as isotropic solid. Hence, the need to develop accurate strain energy functions to understand the mechanical behaviour of transversely isotropic soft tissues. In isotropic elasticity, phenomenological strain energy functions with principal stretches have certain attractive features from both the mathematical and physical viewpoints. These forms of strain energy have been widely and successfully used in prediction of elastic deformations. This research is an extension from classical invariants of isotropic models to characterize transversely isotropic soft tissues with spectral invariants. In order to obtain a specific form of the strain energy function from an experiment, it is convenient to have explicit and analytic expressions for the derivatives of the strain energy function with respect to its invariants. Three of the invariants are the principal extension ratios and the other two are the cosines of the angles between the principal directions of the right stretch tensor and the material preferred direction. These direct physical interpretations of the invariants shows that the model has an experimental advantage where a triaxial test can vary a single invariant while keeping the remaining invariants fixed. The symmetrical and orthogonal properties developed here are similar to that possessed by a strain energy function of an isotropic elastic solid written in terms of principal stretches. A specific constitutive model was applied to biological soft tissues and the model compares well with existing experimental data.
format Thesis
qualification_name Doctor of Philosophy (PhD.)
qualification_level Doctorate
author Ayem, Mahad
author_facet Ayem, Mahad
author_sort Ayem, Mahad
title Modelling of transversely isotropic nonlinear incompressible soft tissues using spectral invariants
title_short Modelling of transversely isotropic nonlinear incompressible soft tissues using spectral invariants
title_full Modelling of transversely isotropic nonlinear incompressible soft tissues using spectral invariants
title_fullStr Modelling of transversely isotropic nonlinear incompressible soft tissues using spectral invariants
title_full_unstemmed Modelling of transversely isotropic nonlinear incompressible soft tissues using spectral invariants
title_sort modelling of transversely isotropic nonlinear incompressible soft tissues using spectral invariants
granting_institution Universiti Teknologi Malaysia, Faculty of Science
granting_department Faculty of Science
publishDate 2017
url http://eprints.utm.my/id/eprint/79356/1/MahadAyemPFS2017.pdf
_version_ 1747818208532889600