<p> A stress analysis of porcine aortic valve leaflets in diastole at 80 mm. Hg. in-vitro is presented. Incorporations of local surface geometry, leaflet material inhomogeneity, anisotropy and non-linearity are applied. The stress theory used is a modified form of the thin membrane stress theory for a homogeneous, linearly elastic and orthotropic lamina. Modifications are made so that the linear Hooke's Law equations of stress may be applied to the inhomogeneous, non-linearly elastic and orthotropic thin membrane aortic valve leaflets. </p> <p> Stress calculations are made on the premise that the diastolic valve leaflets at 80 mm. Hg. are in pre-transition (that is, characterized by a small elastic modulus) for the circumferential direction, and in post-transition (that is, characterized by a large elastic modulus) for the radial direction. Circumferential stresses are calculated to be relatively negligible; they are estimated to be less than 1 gm/mm². Radial stresses for the non coronary leaflet lie primarily in the 0 to 20 gm/mm² range. The regions of the largest stress concentrations are in the areas of mutual leaflet coaptation, especially near the Nodes of Aranti. A progressive increase of the radial stresses from the sinus annulus edges toward the coaptation edges of the leaflets is also observed. Based on the one valve reported , it appears that the left coronary leaflet is the highest stressed and the right coronary leaflet is the least stressed. Central leaflet radial stresses for the right coronary leaflet are in the 0 to 10 gm/mm² range, as compared to 0 to 20 gm/mm² for the non coronary and left coronary leaflets. </p> <p> The question as to whether the diastolic strains of the valve leaflets are in pre-transition, transition or post-transition is raised. The resolution of the question is seen to be critical to the validity of the stress analysis. It is also realized that further improvements in the analysis are possible through improvements and refinements to the experimental methods used in obtaining the necessary inputs for the analysis. </p> / Thesis / Master of Engineering (ME)
| Identifer | oai:union.ndltd.org:mcmaster.ca/oai:macsphere.mcmaster.ca:11375/17450 |
| Date | 12 1900 |
| Creators | Chong, Ming |
| Contributors | Missirlis, Y. F., Engineering Physics |
| Source Sets | McMaster University |
| Language | English |
| Detected Language | English |
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