Characterization of multilayer material properties of descending aorta

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 quasilinear viscoelastic model. Two layers of equal thickness were mechanically distinguishable based on the radial variations in the instantaneous Young's modulus E and reduced relaxation function G(t). The overall results showed that the outer half was stiffer and showed less relaxation than the inner half. These layers may correspond to media and adventitia in the specimens.