Energy-based Constitutive Modeling of Local Material Properties of Canine Aortas
- This study aims at determining the in vitro anisotropic mechanical behavior 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 fiber orientations. We subsequently characterized a constitutive model that incorporates both phenomenological and structural elements to account for macroscopic and microstructural behavior of the tissue. We showed the two fiber families were oriented at similar angles with respect to aorta’s axis. We also found significant changes in mechanical behavior of the tissue as a function of axial position from proximal to distal direction: the fibers 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 139kPa to 64kPa. 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 fibers, 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.
|Type of resource
|nonlinear hyperelastic constitutive modeling
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