Evaluation of a multi-scale discrete fiber model for analyzing arterial failure

Abstract

So far, the prevalent rupture risk quantification of aortic aneurysms does not consider information of the underlying microscopic mechanisms. Uniaxial tension tests were performed on imaged aorta samples oriented in circumferential and longitudinal directions. To account for local heterogeneity in collagen fiber architecture, SHG imaging was performed on tissues at several locations prior to mechanical testing. This enabled the quantification of micro-scale information including organization of collagen fibers using relevant probability density functions. Two different modeling approaches are presented in this study for the sake of comparison. A multi-scale mechanical model was developed using this micro-structural information with collagen fibers as main components. accounting for non-affine fiber kinematics. Simultaneously, an embedded element model that accounts for affine fiber kinematics was developed in Abaqus using the same micro-structural information. Numerical simulations emulating uniaxial tension experiments were performed on the developed models. Global mechanical response of both models agreed well with the experimental data, although leading to mismatched material properties. The models present a rudimentary yet better than before representation of structure based description of aortic-tissue failure mechanics. reinforcing the importance of structural organization of micro-scale constituents and their kinematics in determining tissue failure.

Keywords: Finite elements; Tunica adventitia; collagen fibers; rupture.