A three‐layer model for buckling of a human aortic segment under specific flow‐pressure conditions

Abstract

Human aortas are subjected to large mechanical stresses because of blood flow pressurization and through contact with the surrounding tissue. It is essential that the aorta does not lose stability by buckling with deformation of the cross-section (shell-like buckling) (i) for its proper functioning to ensure blood flow and (ii) to avoid high stresses in the aortic wall. A numerical bifurcation analysis employs a refined reduced-order model to investigate the stability of a straight aorta segment conveying blood flow. The structural model assumes a nonlinear cylindrical orthotropic laminated composite shell composed of three layers representing the tunica intima, media and adventitia. Residual stresses because of pressurization are evaluated and included in the model. The fluid is formulated using a hybrid model that contains the unsteady effects obtained from linear potential flow theory and the steady viscous effects obtained from the time-averaged Navier-Stokes equations. The aortic segment loses stability by divergence with deformation of the cross-section at a critical flow velocity for a given static pressure, exhibiting a strong subcritical behaviour with partial or total collapse of the inner wall. Preliminary results suggest directions for further study in relation to the appearance and growth of dissection in the aorta.

Over-Wrapping of the Aortic Wall with an Elastic Extra-Aortic Wrap Results in Luminal Creasing

“…The idealized single layered tube geometry is depicted in Figure 1 . Published dimensions of the ascending human aorta vary across published case reports [ 6 , 7 , 8 , 9 ]. We modelled a lumen diameter in the lower range, 20 mm (pre-expansion) [ 10 ].…”

Flow‐induced ATP release in patient‐specific arterial geometries – a comparative study of computational models

“…In contrast, image‐based modelling is an integral part of the proposed approach. An increasing number of studies now address the issues of patient‐specific, image‐based modelling , vascular reconstruction, model reduction and multiscale techniques . Based on a number of previously published results, the present work provides a starting point to a unified approach to modelling the pathways to endothelial dysfunction.…”

Static and Dynamic Behavior of Circular Cylindrical Shell Made of Hyperelastic Arterial Material

“…Are explored the static and dynamic behaviors of a circular cylindrical shell depicted in Fig. 1 with the following geometrical parameters from [6]: radius R D 0:015 75 m, length L D 0:126 m, and thickness h D 0:002 61 m.…”

“…The meshless approach that the authors proposed in the previous studies [10,6,9] is intended to overcome these difficulties. In the present study we extend the method for the case of a thick shell made of special type of hyperelastic material (combination of Neo-Hookean and Fung materials) that is able to reproduce the actual behavior of an arterial tissue [17].…”