医用心血管支架的非线性有限元分析

经过扩张过程获得的医用心血管支架几何形状或力学结构对于其长期的生物相容性是非常重要的，研究支架的扩张过程具有重要的意义。本文采用非线性有限元法模拟了支架的自由扩张。在研究中，将支架扩张的整个过程看成由多个极短的平衡过程组成，在每个过程中支架所受载荷视为常量进行有限元分析，解决了支架所受非线性载荷；利用合适的边界条件，结合BFGS方法，在采用规定某个结点的位移增量以确定载荷增量的办法解决塑性大变形分析中结果不对称的难题下，较好地模拟了支架的自由扩张。计算结果和实验结果吻合得较好。本研究提出的医用心血管支架有限元分析方案是合理的。

THE NONLINEAR FINITE ELEMENTS ANALYSIS OF THE BLOOD VESSEL STENT

Purpose: This paper is to study the invivo deployment of the stent. Methods: Nonlinear finite element was used to simulate the invivo deployment. The expansion process of the stent was considered as composing of many extremely short equilibrium processes, where the loads on the stent was regarded as constants and the algorithm of BFGS was also adopted to solve the negative value of the stiffness appeared. At the same time, the boundary conditions suitable for the stent was used. To avoid the nonsymmetrical results of NFEA of the stent when the loads were irrational, the method proscribing displacement increment of a certain node to define load increment was introduced to the analysis. Finally, experiments were carried out to confirm the calculated results. Results: The simulation of deployment of the stent has accomplished well. The calculated results were consistent with those of experiments. Discussion: Using nonlinear finite element to simulate the deployment was feasible, which could help the design and use of the stent.