A structure-based constitutive model of arterial tissue considering individual natural configurations of elastin and collagen.

The study proposes a novel theoretical-experimental approach for structure-based constitutive modeling of the passive mechanical properties of arterial tissue. The major novelty is accounting for the existence of individual natural configurations of elastin and collagen and their mechanical interaction in terms of the constituents' individual prestretches in the tissue natural state. The structure-based modeling of collagen allows accounting for effects of change in constituents' prestretch in terms of the change in feasible microstructural parameters, such as range of collagen recruitment stretch, mode of collagen mass fraction intensity function, and fiber directions. The results from an illustrative example for a porcine renal artery show that the model is robust and can adequately describe pressure-radius response and the stress-stretch relationship. The predictive capability of the model is tested in simulations of an isolated change in collagen prestretch and of elastin degradation in an artery kept at constant length. We expect this model to advance understanding about arterial rheology and serve as a useful tool for interpreting experimental data and solving boundary value problems relevant to vascular physiology at normal and pathological states.