THE MECHANICAL-PROPERTIES OF SOFT-TISSUES .2. THE ELASTIC RESPONSE OF ARTERIAL SEGMENTS

The mechanical properties of dog aorta were examined using microprocessor based instrumentation described elsewhere. In seven in vitro experiments, specimens were continuously loaded and unloaded axially at a fixed stretch rate while the luminal pressure was continuously varied so as to maintain a constant diameter. Force, length and pressure were recorded digitally and subsequently analyzed using the theory of large elastic deformation. Assuming a circular cylindrical cross-section and homogeneous, incompressible and isotropic behavior, the pressure and force can, for a given load or unload cycle, be expressed in terms of a strain energy density function and initial specimen dimensions. A Taylor series expression for W containing up to four terms resulted in good agreement, in a least squared sense, with the data. Significant differences between loading and unloading cycles and large stress gradients in the walls were observed.