目的 研究考虑尺寸效应的聚合物血管支架力学性能，分析支架结构对支架力学性能和支架变形过程中尺寸效应的影响规律，为支架的结构设计提供理论依据。方法 建立了考虑尺寸效应的聚乳酸的Cosserat理论模型，并结合有限元法，通过三点弯和平板压获得支架弯曲刚度和径向支撑强度，进一步分析了支架的筋厚和筋宽、支撑单元的曲率半径和轴向间距对支架径向支撑性能和尺寸效应强度的影响规律。结果：聚合物血管支架在弯曲和压缩过程中均存在明显的尺寸效应现象；支架的径向支撑强度与支撑单元曲率半径和轴向间距均呈负相关，与筋厚和筋宽均呈正相关；支撑单元的曲率半径、轴向间距以及支架的筋厚和筋宽越小，聚合物血管支架压缩过程中的尺寸效应强度越大。结论 支架的径向支撑性能主要由结构的刚度决定，并受支架变形过程中尺寸效应强度的影响；支架几何结构的特征尺寸越小、支架弯扭变形的程度越大则尺寸效应越明显，对支架径向支撑性能的增幅越大。
Objective In order to provide a theoretical basis for the structural design of stents, the mechanical properties of polymeric vascular stents considering size effect were investigated, and the influence law of stent structure on the mechanical properties of stents and size effect during stent deformation was further analyzed. Methods The Cosserat theoretical model of PLA considering size effect was established, and combined with the finite element method, the bending stiffness and radial support strength of the stent were obtained by three-point bending and flat plate compression, and the influence laws of the rib thickness and rib width of the stent, the radius of curvature and axial spacing of the bracing unit on the radial support performance and size effect strength of the bracket were further analyzed. Results there was significant size effect in both bending and compression of the polymeric vascular stent. The radial support strength of the support unit is negatively correlated with the radius of curvature and axial spacing, and positively correlated with the rib thickness and rib width, and the smaller the radius of curvature, axial spacing, rib thickness and rib width of the support unit, the larger the size effect strength in compression. Conclusions the radial support performance of the stent is mainly determined by the stiffness of the structure and is affected by the strength of the size effect in the process of structural deformation. The smaller the characteristic dimensions of the stent structure and the greater the degree of stent’s bending and twisting deformation, the more pronounced the size effect and the greater the increase in the radial support performance of the stent.