Estimation of the 3D residual strain field in the arterial wall of a bovine aorta using optical full-field measurements and finite element reconstruction

Arterial tissue consists of multiple types of structurally important constituents, each of which may have individual material properties and associated stress-free configurations that may evolve over time. This gives rise to residual stresses which contribute to the homeostatic state of stress in vivo as well as adaptations to perturbed loads, disease, or injury. The existence of residual stress in an intact but traction-free excised arterial segment suggests compressive stresses in the inner wall and tensile stresses in the outer wall. Accordingly, an artery ring springs open into a sector after a radial cut. The measurement of the opening angle is used to deduce the residual stresses, which are actually the stresses required to close back the ring. The open angle method provides an average estimate of circumferential residual stresses but it gives no information on either the local distribution through the thickness and along the axial direction. To address this lack, we propose to derive maps of residual stresses using a novel approach based on the contour method. Small pieces of freshly excised tissue are carefully cut into the specimen and the local distribution of residual stresses is determined from whole-body DIC measurements using a finite element model.