High Amplitude Torsional Shear of Porcine Thoracic Aorta

Abstract

Studying the mechanics of aortic tissue is a crucial component in understanding its behavior under healthy as well as diseased conditions. Wall shear stress and circumferential stress have been largely accepted as significant factors in arterial growth and remodeling as a response to changes in flow and pressure. But, experimental studies on aortic tissues have largely focused on uniaxial and biaxial tests which are more suited for investigating circumferential stress. This may be explained by the inherent convenience of gripping tissue and then applying deformations in the uniaxial and biaxial modes. As such, the behavior of aortic tissue under shear has been left relatively unstudied. We propose to study the response of porcine aortic wall tissue under cyclic constant torsional shear strain rate for high amplitude (50%) and at different shear strain rates (4%/s and 40%/s). Three to four 12.5 mm diameter samples are obtained from the descending porcine aorta. Initial results clearly indicate a non linear response for the moment as a function of the angle of twist while many popular models predict a linear response for the arterial wall even under large shear strain.