Non-linear finite element analyses of the aortic heart valve

 

Show simple item record

dc.contributor.advisor Reddy, B Daya en_ZA
dc.contributor.author Koch, Thorsten M en_ZA
dc.date.accessioned 2014-08-29T12:43:34Z
dc.date.available 2014-08-29T12:43:34Z
dc.date.issued 2004 en_ZA
dc.identifier.citation Koch, T. 2004. Non-linear finite element analyses of the aortic heart valve. University of Cape Town. en_ZA
dc.identifier.uri http://hdl.handle.net/11427/6756
dc.description Includes bibliographical references. en_ZA
dc.description.abstract 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. en_ZA
dc.language.iso eng
dc.subject.other Applied Mathematics en_ZA
dc.title Non-linear finite element analyses of the aortic heart valve en_ZA
dc.type Thesis
uct.type.publication Research en_ZA
uct.type.resource Thesis en_ZA
dc.publisher.institution University of Cape Town
dc.publisher.faculty Faculty of Science en_ZA
dc.publisher.department Department of Mathematics and Applied Mathematics en_ZA
uct.type.filetype Text
uct.type.filetype Image
dc.identifier.apacitation Koch, 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/11427/6756 en_ZA
dc.identifier.chicagocitation Koch, 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/11427/6756 en_ZA
dc.identifier.vancouvercitation Koch 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/11427/6756 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


Files in this item

This item appears in the following Collection(s)

Show simple item record