Atherosclerosis Research Center, Baqiyatallah University of Medical science, Tehran, Iran.
Mechanical Engineering Department, Sahand University of Technology, Tabriz, Iran.
Mater Sci Eng C Mater Biol Appl. 2017 Apr 1;73:182-188. doi: 10.1016/j.msec.2016.12.034. Epub 2016 Dec 20.
Undesirable deformation of the stent can induce a significant amount of injure not only to the blood vessel but also to the plaque. The objective of this study was to reduce/minimize these undesirable deformations by the application of Functionally Graded Materials (FGM). To do this, Finite Element (FE) method was employed to simulate the expansion of a stent and the corresponding displacement of the stenosis plaque. Three hyperelastic plaque types as well as five elastoplastic stents were simulated. Dogboning, foreshortening, maximum stress in the plaque, and the pressure which is needed to fully expand the stent for different stent materials, were acquired. While all FGMs had lower dogboning in comparison to the stents made of the uniform materials, the stent with the lowest heterogeneous index displayed the lowest amount of dogboning. Steel stent showed the lowest foreshortening and fully expansion pressure but the difference was much lower than that the one for dogboning. Therefore, the FGM with the heterogeneous index of 0.5 is expected to exhibit the most suitable results. In addition, the results revealed that the material parameters has crucial effects on the deformation of the stent and, as a result, as a design point of view the FGM parameters can be tailored to achieve the goal of the biomechanical optimization.
支架的不良变形不仅会对血管造成很大的损伤，还会对斑块造成损伤。本研究的目的是通过应用功能梯度材料（FGM）来减少/最小化这些不良变形。为此，采用有限元（FE）方法模拟支架的扩张和相应的狭窄斑块的位移。模拟了三种超弹性斑块类型和五种弹塑性支架。获得了狗骨变形、缩短、斑块中的最大应力以及完全扩张不同支架材料所需的支架的压力。虽然所有 FGM 的狗骨变形都低于均匀材料制成的支架，但异质指数最低的支架显示出的狗骨变形最小。钢支架显示出最低的缩短和完全扩张压力，但差异远低于狗骨变形。因此，预计异质指数为 0.5 的 FGM 将表现出最适合的结果。此外，结果表明材料参数对支架的变形有至关重要的影响，因此，从设计角度来看，可以调整 FGM 参数以实现生物力学优化的目标。
