UNIAXIAL AND BIAXIAL MECHANICAL PROPERTIES OF THE HUMAN SAPHENOUS VEIN

Abstract

Cardiovascular diseases are one of the major causes of death in the world and are closely related to blood dynamics and wall mechanical properties of vessels. This makes the study of mechanical properties of arteries and veins essential. In this regard, study on common vessels used in bypass grafting operations is of special importance due to the frequency of this surgery. Human saphenous vein is one of the vessels used for bypass surgeries. The objective of the present study is to characterize the behavior of human saphenous vein using uniaxial and biaxial planar tests. Forty human saphenous samples were obtained after coronary artery bypass surgery (CABG). The planar tensile tests were performed on the tissue specimens by applying loads along two directions. These tests provided the force-displacement curves. The stress-strain curves from uniaxial tests were modeled with a mathematical function and the Young modulus was obtained in both longitudinal and circumferential directions. Measured data of uniaxial tests were then fitted into a hyperelastic four-parameter Fung-type model and also an isotropic Mooney–Rivlin model. The biaxial stress-stretch curves were fitted to a hyperelastic anisotropic four-parameter Fung-type model and a five-parameter Mooney–Rivlin model. The specimens showed some degrees of anisotropy. In both uniaxial and biaxial tests, specimens showed stiffer behaviour in longitudinal as opposed to circumferential directions. The stretch ratio in the circumferential direction was much higher than in the longitudinal orientation.