Finite element analysis of abdominal aortic aneurysms: geometrical and structural reconstruction with application of an anisotropic material model

Computational biomechanics of abdominal aortic aneurysms (AAAs) made it possible to investigate several aspects of the disease and to provide information that would otherwise be difficult to obtain from experiments; the determination of wall stress distributions and rupture risk are two examples. A very few anisotropic strain-energy functions aim to capture vascular biomechanics and involve some coding to specify the collagen fibre orientations. In this study, we developed a solid mechanics framework for the use within Abaqus v. 6.10 (SIMULIA, Providence, RI, USA) with the aim to model the anisotropic response of AAAs in a robust and straightforward way. The proposed framework contains: (i) geometry reconstruction allowing flexible meshing; (ii) generation of 3D centrelines for each arterial branch; (iii) robust assignment of 3D collagen fibre orientation; (iv) AAA parameters for the Holzapfel-Gasser-Ogden model implemented in Abaqus. In the result section, we reproduce published stresses of an idealized geometry under physiological pressure with a difference of 4.41%, and apply the framework to patient-specific geometries. Finally, the simulation of an AAA deformed by two catheters during endovascular aortic repair is demonstrated.