An isotropic neo-hookean finite element model of healthy elastic arterial walls within commercial software

Abstract

A non-linear isotropic finite element model of an elastic arterial wall is developed within the ANSYS commercial software package. While progressively increasing complexity of the model, it is validated with analytical theory. Geometric nonlinearity is investigated and an iterative convergence method for the calculation of a solution-dependent axial force, which increases with artery deformation, is presented. Neo-Hookean hyperelastic material models are fitted to existing uniaxial, biaxial, and shear experimental data from literature for both rubber and polyurethane elastomer to introduce material nonlinearity into the arterial wall model. A mesh independence study was performed to determine a suitable mesh and the elastomer materials were simulated, with the resulting pressure-diameter responses compared to a real artery. Finally, the arterial wall model was fitted to existing experimental results for a rat carotid artery and a human subclavian artery, and the mechanical responses were compared. It was found that the model simulated the behaviour of the rat carotid artery well for up to 15% diametral strain with a root-mean-square error (RMSE) of 0.43 mm Hg. For the human subclavian artery model, the behaviour did not match well, with the pressure-diameter response diverging from the real artery after 2% diametral strain. However, it had a RMSE of 0.94 mm Hg below 2% diametral strain. Recommendations for further investigation are made to improve the model.