Computational study of influence of materials properties on Nitinol shape memory alloy stents behavior for application in trachea lumen

Simulation of Nitinol shape memory alloy stents behavior for application in trachea stent implantation has been strategically used for solving trachea stenosis. Predicaments like insufficient radial strength, low twisting ability, inappropriate dynamic behavior and restenosis are expected to be solved by the introduction of new designs. Superelastic shape memory alloy stent is an interesting alternative for minimizing these tight spots. The application of finite element method to predict metallurgical of superelastic shape memory alloy stents for trachea duct dilatation is supported by conventional crimp tests. The present simulation modeled the stent material’s superelasticity based on Auricchio theories (Helmholtz free energy) and Lagoudas (Gibbs free energy).Nitinol shape memory alloy stents with material properties contain Af temperature of 24°C° is shown to have the best mechanical performance for clinical applications. Owing to lower chronic outward force (COF), higher radial resistive force (RRF), and more suitable superelastic behavior. Model calculations showed that a very high change of Af temperature could exert a substantial effect on practical performance of the stent. This FEM model can provide a convenient way for evaluation of biomechanical properties of peripheral stents given to effects of metallurgical properties such as austenite finish temperature.