A continuum description of the damage process in the arterial wall of abdominal aortic aneurysms

Abstract

In the present work, we develop a three-dimensional isotropic finite-strain damage model for abdominal aortic aneurysm (AAA) wall that considers both the characteristic softening of the material caused by damage and the spatial variation of the material properties. A strain energy function is formulated that accounts for a hyperelastic, slightly compressible, isotropic material behavior during the elastic phase, whereas the damage process only contributes to the material response when the elastic limit of the AAA wall is exceeded. Material and damage parameters are obtained by fitting the strain energy function to the experimental data obtained by uniaxial tensile tests of freshly harvested AAA wall samples. The damage model extends the validity of the material law to a strain range of up to 50%. Purely elastic material laws for AAA wall are only valid for a strain range of up to 17%. In a series of finite element simulations of patient-specific AAAs, serving as numerical examples, we investigate the applicability of the damage model. The use of the damage model does not yield a more distinct identification of rupture-prone AAAs than other computational-based risk indices. However, the benefit of the finite-strain damage model is the potential capability to trigger growth and remodeling processes in mechanobiological models.

Interaction of Biomechanics with Extracellular Matrix Components in Abdominal Aortic Aneurysm Wall

“…After applying 19 cycles of preconditioning, the data of the 20th cycle were used for evaluation. 7,11,14,17 Following the cyclic experiment, specimens underwent destructive testing to measure the failure load. In both cases, the applied force and the clamp displacement were recorded.…”

Layer-dependent wall properties of abdominal aortic aneurysms: Experimental study and material characterization

“…Still, all past studies, e.g. (He and Roach, 1994;Raghavan et al, 1996;Raghavan and Vorp, 2000;Thubrikar et al, 2001;Vallabhanemi et al, 2004;Vande Geest et al, 2006a,b;Di Martino et al, 2006;Raghavan et al, 2011;Marini et al, 2012;Forsell et al, 2013;Reeps et al, 2013;Tong et al, 2013;Tavares Monteiro et al, 2014;O'Leary et al, 2014aO'Leary et al, , 2015Pierce et al, 2015), have considered the AAA wall tissue as intramurally homogeneous. The varying loadbearing capacity of wall layers has been presented for ascending aortic aneurysms (Sokolis et al, 2012a) and the non-dilated abdominal aorta (Weisbecker et al, 2012), but not for AAA and such data have not been included in the wall stress analysis studies hitherto performed; see the bibliography in Vorp (2007), Phillippi et al (2011), Humphrey and Holzapfel (2012).…”

Adjoint-based inverse analysis of windkessel parameters for patient-specific vascular models

“…Computational modeling, using finite element (FE) has proven to be a very useful and important tool for better understanding biomechanical and hemodynamical behavior of vasculature diseases [1][2][3][4][5][6]. This is particularly significant for diseased arteries such as aneurysmatic or stenosed arteries.…”