TWO-DIMENSIONAL FINITE DEFORMATION EXPERIMENTS ON DOG'S ARTERIES AND VEINS.
Scientific interim rept.,
CALIFORNIA UNIV SAN DIEGO LA JOLLA DEPT OF THE AEROSPACE AND MECHANICAL ENGINEERING SCIENCES
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Most published data on the blood vessel elasticity were obtained either in simple elongation or in simple inflation, but not simultaneously. For finite deformations, such data are insufficient to formulate a three-dimensional stress-strain law even if the material is isotropic and incompressible. Since the blood vessels are highly nonlinear, the Youngs modulus for a specimen varies continuously from almost zero at the undeformed state to a large final value, and a starement of the modulus without the corresponding stress level is meaningless. The purpose of the experiments reported in this paper is to illustrate a scheme remedying these difficulties. The tests consist of 1 a longitudinal stretching while the diameter of the vessel was maintained, 2 a lateral distension with the length of the vessel fixed, 3 stress relaxation at fixed strain, and 4 cyclic deformation. Two Lagrangian stresses stresses based on the vessels undeformed state and two extension ratios are used to describe the deformed state of the vessel under a symmetric loading. The nonlinearity in the elasticity, and the dependence of the stress on the strain-history is demonstrated. Author
- Anatomy and Physiology