Modelling the anisotropic behaviour of filament wound vascular grafts

The model according to the Law of Laplace, describing the mechanical behaviour of blood vessels and vascular grafts, was applied to filament wound arterial prostheses, which have been manufactured with different winding angles. By varying the winding angle, the anisotropic behaviour of the grafts could be changed and fitted to the anisotropic properties of natural blood vessels. Thus, the Laplace model had to be modified, and answers now to the requirement of responding to the anisotropic behaviour in hoop versus axial direction of the grafts. The experimental data of hoop and axial compliances obtained by biaxial inflation tests could be then correlated to the material properties of the vascular grafts measured by uniaxial tensile loading. It is shown that with the modified Laplace model the changes in the anisotropic behaviour due to different winding angles can be described and predicted. The calculated compliance values derived from the uniaxial tensile tests fitted the experimental data obtained by the biaxial inflation tests, although the calculated hoop compliance values tended to be higher than the experimental data.