title: Energy-based constitutive modelling of local material properties of canine aortas.
abstract: This study aims at determining thein vitroanisotropic mechanical behaviour of canine aortic tissue. We specifically focused on spatial variations of these properties along the axis of the vessel. We performed uniaxial stretch tests on canine aortic samples in both circumferential and longitudinal directions, as well as histological examinations to derive the tissue's fibre orientations. We subsequently characterized a constitutive model that incorporates both phenomenological and structural elements to account for macroscopic and microstructural behaviour of the tissue. We showed the two fibre families were oriented at similar angles with respect to the aorta's axis. We also found significant changes in mechanical behaviour of the tissue as a function of axial position from proximal to distal direction: the fibres become more aligned with the aortic axis from 46° to 30°. Also, the linear shear modulus of media decreased as we moved distally along the aortic axis from 139 to 64 kPa. These changes derived from the parameters in the nonlinear constitutive model agreed well with the changes in tissue structure. In addition, we showed that isotropic contribution, carried by elastic lamellae, to the total stress induced in the tissue decreases at higher stretch ratios, whereas anisotropic stress, carried by collagen fibres, increases. The constitutive models can be readily used to design computational models of tissue deformation during physiological loading cycles. The findings of this study extend the understanding of local mechanical properties that could lead to region-specific diagnostics and treatment of arterial diseases.
authors.affiliation: Department of Bioengineering , Stanford University , Stanford, CA , USA.
authors.forename: Kaveh
authors.identifier: 0000-0001-5985-5378
authors.initials: K
authors.lastname: Laksari
authors.affiliation: Department of Mechanical Engineering , Stevens Institute of Technology , Hoboken, NJ , USA.
authors.forename: Danial
authors.initials: D
authors.lastname: Shahmirzadi
authors.affiliation: Ultrasound and Elasticity Imaging Lab (UEIL), Department of Biomedical Engineering , Columbia University , New York, NY , USA.
authors.forename: Camilo J
authors.initials: CJ
authors.lastname: Acosta
authors.affiliation: Ultrasound and Elasticity Imaging Lab (UEIL), Department of Biomedical Engineering, Columbia University, New York, NY, USA; Department of Radiology, Columbia University, New York, NY, USA.
authors.forename: Elisa
authors.initials: E
authors.lastname: Konofagou
keywords: aortic tissue; histology; nonlinear hyperelastic constitutive modelling