Validation of Nitinol peripheral stents fatigue risk of fracture through in vitro cyclic axial tests

Treatment of stenotic lower limbs is commonly performed using Nitinol peripheral stents. However, the large and cyclic deformations of the femoral arteries might cause long-term failure of the implanted device. Finite element analysis (FEA) may be a useful tool to study the in vivo stent fatigue behavior. A preliminary investigation to verify the predictive capability of fatigue computational analyses should be performed using simple and well-controlled experimental tests. This study consists of a combined numerical-experimental activity, aimed at the validation of the fatigue FEA. In particular we experimentally investigated the fatigue behavior of a commercial stent when subjected to cyclic axial compression, in the expanded configuration and after the implantation in a silicon tube, resembling the arterial vessel. An experimental set-up to impose the tube pre-stretch (10% of the tube length) in a controlled way was developed. The experimental tests were reproduced by means of FEA. The numerical results were compared with experimental evidences and revealed good agreement.