Computational evaluation of the effect of geometric parameters on the mechanical performance of shape memory alloy stents for use in the breathing systems

In the present study, the finite element method was used to study the effects of geometric parameters on superconductive behavior of new geometries Z- Shape of shape memory alloy stent for application in the trachea using a radial loading(crimping) test. The material model used to describe the properties of a shape memory material based on the Helmholtz free thermodynamic energy (Aurichio model). In this numerical study by creating a new design of the stent and by choosing different mechanical properties and changing its geometric parameters, the mechanical performance of the stents was evaluated using finite element analysis with empirical verification. The modified geometric parameters are the thickness, number of vertices and angles between the stents. Reducing the thickness of the stents from 0.3 to 0.2 in the same of angle between the length and the number of bends of the stent causes reducing the stiffness = 37.87%, reducing the radial mechanical strength to open ducts (COF) = 50%, reducing the radial force = 38.35% and increasing displacement = 0.2%. The stents with lower thickness have a better mechanical performance due to more complete mechanical hysteresis loop, less radial mechanical strength to open ducts(COF), more radial resistive mechanical strength related to ducts(RRF), less radial force, less stiffness, more displacement, less stress ,high strain at stent critical points, and high martensite formation at less strain.