Finite element modeling and numerical simulation of the artery in active state

A layer-structured finite element model is introduced for an artery, which consists of passive and active elements and is applicable to a variety of boundary-value problems. Constitutive equations are formulated for each type of element in the finite element model. The passive element is expressed as an incompressible isotropic hyperelastic material. The active element develops an active stress in the circumferential direction. To validate the model, we carried out numerical simulations, i.e., the pressure-diameter relationships and stress distributions at mean transmural pressure in the passive and active states, and the opening angle change with activation. The results of numerical simulation showed significant changes in the mechanical behavior of the vessel with activation. It also showed that a large contraction occurred at a higher level of activation for a higher level of constant pressure, and that the tendency of opening angle change was consistent with the experimental one reported in the literature.