PREDICTION OF PLANAR UNIAXIAL AND CONSTRAINED BIAXIAL STATE OF DEFORMATION BY COMMONLY USED ANISOTROPIC CONSTITUTIVE MODELS IN ARTERIAL MECHANICS

In this paper is investigated mechanical response of tissue strips under planar simple tension and constrained biaxial tension (strain behavior by Humprey) for a representative selection of two- and three-dimensional anisotropic strain energy functions, commonly used in arterial mechanics: Fung’s 2D and 3D models, logarithmic, polynomial and exponential Choi and Vito 2D models, and structural exponential 3D model for artery layers. It has shown that all these models have limitations in capability of describing the considered states of deformation. By using material parameters from literature it was found that there are a considerable number of cases where unrealistic material response might be predicted, if the parameters are outside of the range for which fitting process was performed. In order to avoid instability of computed material response, we suggest that uniaxial loading conditions should be considered, together with constrained biaxial tension, in experimental investigations for establishing new material model or fitting constants of a selected model.