AORTIC-VALVE MECHANICS .2. STRESS ANALYSIS OF PORCINE AORTIC-VALVE LEAFLETS IN DIASTOLE

Stress analysis of the porcine aortic valve leaflets in diastole at 80 mm Hg pressure in-vitro is presented. Incorporation of local geometrical asymmetry, material inhomogeneity, anisotropy and nonlinearity 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 Hooke's law constitutive equations of stress may be applied to the inhomogeneous, nonlinearly elastic and orthotropic thin (membrane) aortic valve leaflets. Stress calculations are made on the premise that the valve is in pre-transition (i. e. low elastic modulus) in the circumferential direction and post-transition (i. e. high elastic modulus) in the radial direction. It is shown that sigma (CIR) less than 1 gm/mm**2, and for most of the noncoronary leaflet, 0 less than sigma (RAD) less than 30 gm/mm**2. The areas of highest stress concentrations are in the areas of mutual leaflet coaptation near the Node of Arantii. A progressive increase of radial stresses from the sinus-annulus edge toward the node is observed.