Non-linear finite element analyses of the aortic heart valve

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dc.contributor.advisorReddy, B Dayaen_ZA
dc.contributor.authorKoch, Thorsten Men_ZA
dc.date.accessioned2014-08-29T12:43:34Z
dc.date.available2014-08-29T12:43:34Z
dc.date.issued2004en_ZA
dc.descriptionIncludes bibliographical references.en_ZA
dc.description.abstractFinite element models of the aortic heart valve have been successfully used in the past to gain insight into the mechanics of the valve and to aid in understanding of valve failure. Moreover such models are indispensable tools for further developments in heart valve prosthetic design. In previous stress analyses linear elastic constitutive models have predominantly been used to model aortic valve leaflets, despite aortic valve tissue showing highly non-linear behaviour in tension tests. In view of recent developments towards tissue engineering of heart valves, these linear constitutive models of aortic valve leaflets are not likely to produce results sufficiently accurate to correlate cell behaviour with mechanical stimuli. To study how non-linear material behaviour affects the results of stress analyses of the aortic valve, static finite element analyses of the valve including the aortic root and leaflets have been carried out. An isotropic linear elastic material model was assigned to the aortic root with Young's modulus adjusted for the simulated compliance to match physiological values. Linear elastic models for the aortic valve leaflets with parameters used in previous studies were then compared with hyperelastic materials. The parameters used for the exponential strain energy function of the latter were obtained from fits of uniaxial tension test results of fresh porcine aortic valve leaflets. As natural leaflets show anisotropy with a pronounced stiff direction along the circumference of the valve, isotropic models of the leaflets were extended to account for this behaviour by incorporating transverse isotropy. The results display a stark impact of a transversely isotropic hyperelastic material on leaflet mechanics, Le. increased coaptation with peak values of stress and strain in the elastic limit. Interestingly, the alignment of maximum principal stress of all models seems to approximately follow the coarse collagen fibre distribution found ill aortic valve leaflets.en_ZA
dc.identifier.apacitationKoch, T. M. (2004). <i>Non-linear finite element analyses of the aortic heart valve</i>. (Thesis). University of Cape Town ,Faculty of Science ,Department of Mathematics and Applied Mathematics. Retrieved from http://hdl.handle.net/11427/6756en_ZA
dc.identifier.chicagocitationKoch, Thorsten M. <i>"Non-linear finite element analyses of the aortic heart valve."</i> Thesis., University of Cape Town ,Faculty of Science ,Department of Mathematics and Applied Mathematics, 2004. http://hdl.handle.net/11427/6756en_ZA
dc.identifier.citationKoch, T. 2004. Non-linear finite element analyses of the aortic heart valve. University of Cape Town.en_ZA
dc.identifier.ris TY - Thesis / Dissertation AU - Koch, Thorsten M AB - Finite element models of the aortic heart valve have been successfully used in the past to gain insight into the mechanics of the valve and to aid in understanding of valve failure. Moreover such models are indispensable tools for further developments in heart valve prosthetic design. In previous stress analyses linear elastic constitutive models have predominantly been used to model aortic valve leaflets, despite aortic valve tissue showing highly non-linear behaviour in tension tests. In view of recent developments towards tissue engineering of heart valves, these linear constitutive models of aortic valve leaflets are not likely to produce results sufficiently accurate to correlate cell behaviour with mechanical stimuli. To study how non-linear material behaviour affects the results of stress analyses of the aortic valve, static finite element analyses of the valve including the aortic root and leaflets have been carried out. An isotropic linear elastic material model was assigned to the aortic root with Young's modulus adjusted for the simulated compliance to match physiological values. Linear elastic models for the aortic valve leaflets with parameters used in previous studies were then compared with hyperelastic materials. The parameters used for the exponential strain energy function of the latter were obtained from fits of uniaxial tension test results of fresh porcine aortic valve leaflets. As natural leaflets show anisotropy with a pronounced stiff direction along the circumference of the valve, isotropic models of the leaflets were extended to account for this behaviour by incorporating transverse isotropy. The results display a stark impact of a transversely isotropic hyperelastic material on leaflet mechanics, Le. increased coaptation with peak values of stress and strain in the elastic limit. Interestingly, the alignment of maximum principal stress of all models seems to approximately follow the coarse collagen fibre distribution found ill aortic valve leaflets. DA - 2004 DB - OpenUCT DP - University of Cape Town LK - https://open.uct.ac.za PB - University of Cape Town PY - 2004 T1 - Non-linear finite element analyses of the aortic heart valve TI - Non-linear finite element analyses of the aortic heart valve UR - http://hdl.handle.net/11427/6756 ER - en_ZA
dc.identifier.urihttp://hdl.handle.net/11427/6756
dc.identifier.vancouvercitationKoch TM. Non-linear finite element analyses of the aortic heart valve. [Thesis]. University of Cape Town ,Faculty of Science ,Department of Mathematics and Applied Mathematics, 2004 [cited yyyy month dd]. Available from: http://hdl.handle.net/11427/6756en_ZA
dc.language.isoeng
dc.publisher.departmentDepartment of Mathematics and Applied Mathematicsen_ZA
dc.publisher.facultyFaculty of Scienceen_ZA
dc.publisher.institutionUniversity of Cape Town
dc.subject.otherApplied Mathematicsen_ZA
dc.titleNon-linear finite element analyses of the aortic heart valveen_ZA
dc.typeThesis
uct.type.filetypeText
uct.type.filetypeImage
uct.type.publicationResearchen_ZA
uct.type.resourceThesisen_ZA
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