Identification of the material parameters of an aortic wall

Lukáš Horný, Rudolf Žitný, Hynek Chlup, Hana Macková

Abstract


The passive mechanical response of arterial walls continues to be a topic of great interest. Inflation tests with human thoracic aorta specimens were performed with the aim of fitting a material model. The experimental data was used in a nonlinear regression analysis to identify the material parameters. The aortic tissue was assumed to be an incompressible hyperelastic material. We used a 5–parameter strain energy density function based on a combination of an isotropic Neo–Hookean expression and a Fung–type orthotropic expression. The computational model for identifying the material parameters was based on the boundary value problem of an inflated thick–walled tube with axial pre–strains. The circumferential residual strains were included. The internal structure of the arterial walls was not considered. The fitted material models correspond very well with the experimental data. Significant stiffening under large strains was observed. It was concluded that the combined model of the strain energy density function is suitable for the aortic mechanical response description. The material parameters satisfy the convexity conditions.

Keywords


Aorta; constitutive modeling; Fung-type model; inflation test; hyperelasticity; Neo-Hookean model

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ISSN 1801-1217 (Print)
ISSN 1805-9422 (Online)
Published by the Czech Technical University in Prague, Faculty of Mechanical Engineering