北京生物医学工程

编织支架弯曲变形时扁平现象的数值模拟研究

Numerical simulation of flattening phenomenon in braided stent during bending deformation

作者：付文宇李立新乔爱科

单位：北京联合大学机器人学院(北京 100027) 北京工业大学环境与生命学部(北京100124)

分类号：R318.01

出版年·卷·期（页码）：2020·39·5（455-461）

摘要：

目的编织支架通常用于介入治疗脑动脉瘤或动脉狭窄。在弯曲变形时，编织支架有可能出现截面扁平现象。而在弯曲变形过程中保持其截面形状不变，是编织支架实现介入治疗疗效的必要条件。因此，有必要对编织支架编织角、金属丝根数、轴向长度及名义直径和扁平现象的关系进行定量研究。方法首先使用参数化造型方法构造具有不同的编织角度、金属丝根数、轴向长度和名义直径的19个编织支架模型；然后对这些模型在纯弯曲过程中的扁平现象用Abaqus / Explicit进行计算分析；最后与实验数据进行对比，验证有限元分析结果。结果力学计算表明编织角大于50?时扁平率小于0.0022；随着弯曲角度的增大，扁平率也增大；编织角为60?或70?时，编织支架轴向长度对扁平率基本没有影响；编织角为50?时，支架轴向长度增加，扁平率逐渐减小。编织角为30?，名义直径从2 mm增加到5 mm，扁平率在0.26~0.46之间变化。编织角30?，轴向长度35mm,支架金属丝根数从12增加到48，扁平率从接近为0迅速增加到0.607。结论编织支架弯曲变形时扁平现象的数值模拟结果可以为临床应用中编织支架的结构设计提供理论指导。

Objective Braided stent is usually used for interventional treatment of cerebral aneurysm or arterial stenosis. During the bending deformation, flattening phenomenon may occur. To achieve the therapeutic effect of the braided stent, a necessary condition is that its cross-sectional shape keeps unchanged during the bending deformation. Therefore, the quantitative effects of the braiding angle, the number of wires, axial length and nominal diameter on the flattening phenomenon of the cross section during bending deformation are studied. Methods Firstly， nineteen models of braided stent were constructed, which have different braiding angles, axial lengths，nominal diameter and the number of wires. Then the evaluation of flattening phenomenon was conducted using Abaqus / Explicit. Finally，the numerical results of finite element analysis were validated by comparison with the data of the experiment. Results The flattening ratio was less than 0.0022 when the braiding angle was greater than 50 degree; as the bending angle increased, the flattening ratio also increased; when the braiding angle was 60 degree or 70 degree, the axial length of the braided stent had almost no effect on the flattening ratio; when the braiding angle was 50 degree, the flatten ratio gradually decreased as the axial length of the stent increased. The braiding angle was 30 degree, the nominal diameter increased from 2mm to 5mm, and the flattening ratio varied from 0.26 to 0.46. The flatten ratio increased rapidly from close 0 to 0.607 as the number of wires increased from 12 to 48 (braiding angle was 30 degree and the axial length was 35 mm). Conclusions Numerical simulation of flattening phenomenon in braided stent during bending deformation can provide theoretical guidance for the structural design of braided stents in clinical applications.

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