Structure-based constitutive model can accurately predicts planar biaxial properties of arotic wall tissue

journal article in Web of Science

English

Introduction. Structure-based constitutive models might help exploring mechanisms by which arterial wall histology is linked to wall mechanics. This study aims at validating a recently proposed structure-based constitutive model. Specifically, the models ability to predict mechanical biaxial response of porcine aortic tissue with predefined collagen structure was tested. Materials and Methods. Histological slices from porcine thoracic aorta wall (n=9) were automatically processed to quantify the collagen fiber organization, and mechanical testing identified non-linear properties of the wall samples (n=18) over a wide range of biaxial stretches. Histological and mechanical experimental data was used to identify model parameters of a multi-scale constitutive description for arterial layers proposed recently. The model predictive capability was tested with respect to interpolation and extrapolation. Results. Collagen in the media was predominantly aligned in circumferential direction (planar von Mises distribution with concentration parameter b_M=1.03±0.23), and its coherence decreased gradually from the luminal to the abluminal tissue layers (inner media: b=1.54±0.40; outer media: b=0.72±0.20). In contrast, the collagen in the adventitia was aligned almost isotropically (b_A=0.27±0.11), and no features like families of coherent fibers were identified. The applied constitutive model captured the aorta biaxial properties accurately (coefficient of determination R^2=0.95±0.03) over the entire range of biaxial deformations and with physically meaningful model parameters. Good predictive properties, well outside the parameter identification space, were observed (R^2=0.92±0.04). Conclusions. Multi-scale constitutive models equipped with realistic micro-histological data can predict macroscopic non-linear aorta wall properties. Collagen largely defines already low strain properties of media, which explains the origin of wall anisotropy seen at this strain level. Structure and mechanical properties of adventitia are well designed to protect the media from axial and circumferential overloads

biaxial testing; collagen structure; thoracic aorta; constitutive modeling

POLZER, S.; GASSER, T.; NOVÁK, K.; MAN, V.; TICHÝ, M.; SKÁCEL, P.; BURŠA, J.

2015

10. 1. 2015

Elsevier

London

1742-7061

Acta Biomaterialia

14

1

United Kingdom of Great Britain and Northern Ireland

133

145

12