Investigation of 3-D mechanical properties of blood vessels using a new invitro tests system: Results on sheep common carotid arteries

In order to investigate the three-dimensional (3-D) mechanical properties o f blood vessels, a new experimental device is described allowing in vitro s tatic and dynamic measurements on segments of arteries with high technical performances, Static tests are applied to sheep common carotid arteries, Co nsidering a thick-walled cylindrical model of orthotropic material under la rge deformations, a classical 3-D approach based on strain energy density i s used to calculate the resulting mechanical behavior law in radial and cir cumferencial directions and stresses distribution throughout the mall thick ness. Results are presented with reference to unloaded and zero-stress init ial state thanks to simple measurements of inner and outer circumferences. A particular ratio relating the two main stresses (circumferential and long itudinal) is calculated that put into the forth the progressive modificatio ns in the direction of the predominant stress in the wall and the specific radial location where these changes occur. We observe that this point locat ion is a function of the test conditions of the specimen, i,e., stretching length and level of pressure.