Dilation Performance Analysis And Structure Optimization Of Biodegradable Polymer Stent

In recent years, the incidence of cardiovascular and cerebrovascular disease is increasing year by year. As a critical medical devices of minimally invasive interventional treatment of cardiovascular and cerebrovascular diseases, the research of vascular stent, especially biodegradable polymer stent, has received more and more attention. Comparing with metal stent, the advantages of biodegradable polymer stent is that the blood vessel can restore normal contraction after the stent's degradation, which is beneficial to the vascular remodeling. However, because of the weak stiffness of polymer material, the mechanical properties of biodegradable polymer stent is relatively weak in the dilation process, which has become one of the main factors for the development of biodegradable polymer stent. This paper studied on the dilation performance analysis and structure optimization of biodegradable polymer stent. In this paper, the theoretical research results and technical realization method can provide reference for the design of vascular stent.Firstly, a new kind of biodegradable stent structure was put forward in this paper. This structure used a v-shaped linked reinforcement design, which can effectively improve the flexibility of stent., supporting strut adopted rectangular cross section design to ensure the effect of anti-coagulation in a long time. For guaranteeing the stent had sufficient support properties and the materials coverage was maintained in a reasonable range, all of these had laid a solid foundation for the optimization of the structure of the stent.Secondly, the finite element analysis method is used to simulate the process of polymer stent dilation and analyze the dilation properties of stent. The simulation results showed that the stent had a good performance of dilation. And there is no large deformation about the supporting unit in the dilation process. However, in the rebound process of dilation, there were larger radial elastic recoil and foreshortening ratio about the sent.In order to further improve the dilation properties of the stent, the kriging agent model optimization algorithm and the finite element calculation was used to carry out the single objective optimization design.In the optimization design, the geometries of stent were selected as the design variables. The optimization goals is to minimize the radial elastic recoil and foreshortening in the process of stent dilation, respectively. The influence of design variables on the stent radial elastic recoil and foreshortening was also discussed, and the influence regulation of geometrical dimensions on radial elastic recoil and foreshortening was also revealed. The radial elastic recoil and foreshortening ratio of the stent were reduced.Finally, in order to improve the comprehensive mechanics properties of stent dilation, such as reduce the radial elastic recoil and foreshortening ratio, the engineering optimization design theory was combining with kriging surrogate model was used to carry out a multi-objective optimization design. In the optimization design, the geometries of stent were selected as the design variables. The optimization goal is to minimize the radial elastic recoil and foreshortening ratio of stent expansion. After optimization, the radial elastic recoil and foreshortening ratio in of the stent were greatly reduced, and the comprehensive dilation properties of the stent was improved.