Finite Element Analysis Of Mechanical Behavior Of Self-expanding Stent-graft And Its Forming

Due to the advantages of minimally invasive, high efficient and high cure rate, in recent years, the best method to treat the aortic aneurysm disease is stent-graft implantation. However, the stents used in clinic mainly rely on import. Especially, the studies of the analysis and production for wire ring stent-graft are not too much. Meanwhile the current researches on stent production are mainly based on line stereotype. Therefore it needs further exploration for the bending stent-graft production. This dissertation is based on the problems above. The main research contents and results are as follows:(1) Firstly, using the finite element analysis method to analyze the Z-shaped stent and analyze the influence of key design parameters on stent performance when compressing to delivery catheter. The results showed that the stent connecting arc radius, the length of struts, and the number of V-shape struts in circumstance can affect radial resistance. But the stent oversizing has no effect on radial resistance basically. Moreover, it will change the stent radial profile when increasing the connecting arc radius and the number of V-shape struts in circumstance.(2) The pulsation performance after stent implantation and the fatigue durability were studied. The results showed that the stent durability can be adjusted by changing designing key parameters. But when analyzing the stents safety performance, it needs to combine the stent compression performance as well and get a comprehensive evaluation.(3) According to the finite element analysis results, we used Ni-Ti wire to produce the Z-shaped bending stent-graft. The heat treatment process of the stent forming was explored. Through designing and processing of the forming mold, the two-step method to form stent rings was finally obtained. The first is to form the wires to plane Z-shape, and the second is to curve the plane Z-shape structure into cylindrical. Through a series of experiments, we got the best heat treatment process, and finally produced the fully bending stent-graft.