OPTIMIZATION DESIGN OF DEGRADABLE POLYMER VASCULAR STENT STRUCTURE

Due to the low stiffness of polymers, polymeric stent has lower radial support capability compared to metallic stent. Therefore, the width and thickness of the stent are usually increased to improve its radial support capability, which can not only reduce the flexible performance of the stent and the area of the vascular lumen, but also increase the surface coverage and thus increase the risk of in-stent restenosis. In order to design polymeric stent with smaller strut width and thickness and improve its radial support capability, an optimization method combining with Kriging surrogate model and finite element method was used to optimize the geometries of stent. Kriging surrogate model was used to construct the approximate function relationship between design objectives and design variables. Optimized Latin Hypercube Sampling method was used to select the initial sample points. EI function was used to balance global and local search and tend to find the global optimal solution. As an example, ART18Z polymeric stent was studied in this paper. Firstly, the strut width and thickness of the stent were respectively reduced by 0.02 mm, and then the optimization method was used to optimize the key geometric parameters of ART18Z stent. The numerical results show that the overall service performance of ART18Z stent was improved after optimization and the proposed optimization method can be effectively applied to the optimal design of the polymeric stent.