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可降解镁合金支架(MAS)能够改善商用裸支架和药物洗脱支架的长期治疗效果。由于镁合金支架在人体内降解速度太快,限制了其对病变血管的支撑性能。保护性聚合物涂层为镁合金支架提供了一种降低腐蚀速度的有效方法。然而,聚合物涂层在支架扩张时出现的剥离现象是阻碍其运用的一大障碍。在本研究中,分别运用有限元方法和实验方法对一种优化设计的镁合金支架进行了聚合物涂层剥离问题的研究。首先通过90o剥离实验测试,为粘聚区有限元模型提供了临界能量释放率,以此为基础的90o剥离的模拟结果和实验结果吻合良好。运用可靠的粘聚区模型参数,支架-聚合物涂层有限元模型考察了支架在扩张过程中是否会发生涂层剥离现象。本研究为考察支架聚合物涂层剥离现象提供了一种简单可靠的方法,为改善可降解镁合金支架的聚合物涂层性能提出了相应的建议。
The degradable magnesium alloy stent (MAS) can improve the long-term therapeutic efficacy of commercial bare and drug-eluting stents. Due to the degradation rate of magnesium alloy stent in the human body is too fast, limiting its support of vascular lesions. Protective polymer coatings provide an effective method of reducing corrosion rates for magnesium alloy stents. However, the peel-off phenomenon of the polymer coating during stent expansion is a major obstacle to its application. In this study, we studied the problem of polymer coating stripping on an optimized magnesium alloy stent using finite element method and experimental method respectively. First, the 90o peel test was used to provide the critical energy release rate for the cohesive zone finite element model. Based on this, the simulation results of the 90o peel agree well with the experimental results. Using the reliable cohesion zone model parameters, the stent-polymer coating finite element model examines whether the stent stripping occurs during the stent dilation. This study provides a simple and reliable method for investigating the phenomenon of stripping of scaffold polymer coatings. Some suggestions are put forward to improve the performance of polymer coatings on degradable magnesium alloy scaffolds.