• cardiovascular biomechanics
• aneurysm
• FE analysis
• Ansys
• nonlinear regression

Abdominal aortic aneurysm (AAA) is a common degenerative disease of the abdominal aorta that leads to its dilatation and, ultimately, its rupture. Although aneurysmal pathogenesis remains unclear, loss of medial elastin, the primary component of elastic fibres in arteries, is one of the fundamental histopathologic features of aneurysmal degeneration of the abdominal aorta.
The main goal of this thesis was to develop a finite element (FE) model of abdominal aortic aneurysm (AAA) in an ANSYS environment, in order to take into account regional variations for both geometry and material properties. Moreover, particular attention was devoted to the variation of the wall thickness by analyzing experimental data reported in literature. After a thorough investigation of the theory of non-linear hyperelasticity, several solid models were developed by using specific strain-energy functions (SEFs) to describe both healthy and pathological tissues: healthy tissue was used for areas close to the neck, and pathological tissue in the bulge. Additionally a third material model was developed in order to describe the pathological changes in the posterior region and in the transition region between AA and AAA areas. All the SEFs were fitted to experimental data via a weighted nonlinear regression routine developed in Matlab. Sensitivity analyses were performed in order to assess the effects of these additionally geometrical and constitutive parameters.