title: Multilayer material properties of aorta determined from nanoindentation tests.
abstract: In a wide range of biomechanical modeling of aorta from traumatic injury to stent grafts, the arterial wall has been considered as a single homogeneous layer vessel, ignoring the fact that arteries are composed of distinct anatomical layers with different mechanical characteristics. In this study, using a custom-made nanoindentation technique, changes in the mechanical properties of porcine thoracic aorta wall in the radial direction were characterized using a quasi-linear viscoelastic model. Two layers of equal thickness were mechanically distinguishable in descending aorta based on the radial variations in the instantaneous Young's modulus E and reduced relaxation function G(t). Overall, comparison of E and G(∞) of the outer half (70.27±2.47 kPa and 0.35±0.01) versus the inner half (60.32±1.65 kPa and 0.33±0.01) revealed that the outer half was stiffer and showed less relaxation. The results were used to explain local mechanisms of deformation, force transmission, tear propagation and failure in arteries.
authors.affiliation: Department of Mechanical Engineering, College of Engineering, Temple University, 1947N. 12th Street, Philadelphia, PA 19122, USA.
authors.forename: Ali
authors.initials: A
authors.lastname: Hemmasizadeh
authors.forename: Michael
authors.initials: M
authors.lastname: Autieri
authors.forename: Kurosh
authors.initials: K
authors.lastname: Darvish
mesh_terms: D000818:Animals; D001013:Aorta, Thoracic; D002138:Calibration; D004548:Elasticity; D006245:Hardness Tests / Q000295:instrumentation / Q000379:methods*; D055595:Mechanical Phenomena; D036103:Nanotechnology / Q000295:instrumentation / Q000379:methods*; D013552:Swine; D014783:Viscosity