PNNL

Abstract

We present a polyconvex constitutive law for tissues of the aortic outflow tract, based on a novel invariant theory for dispersed transverse isotropy. In contrast to traditional structural constitutive equations, fiber splay is treated in closed-form and thus can easily handle both two- (2D) and three-dimensional (3D) fiber populations. In the 2D, single preferred-direction case, the model accurately fits biaxial data for aortic valve tissue. Extended to two preferred directions, the model accurately fits available uniaxial data for the aortic sinus and aortic wall. Modification of the fiber stress-strain law requires no re-formulation of the constitutive tangent matrix, making the model flexible for different types of soft tissues, and in the case of 3D fiber populations, the model may be suitable for describing passive myocardium. Most importantly, the model is computationally expedient in a finite-element analysis.