高氮无镍不锈钢冠奖动脉支架力学行为的有限元研究

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	高氮无镍不锈钢冠奖动脉支架力学行为的有限元研究
	刘凤
学位类型	硕士
导师	杨柯
	2012
学位授予单位	中国科学院金属研究所
学位授予地点	北京
学位专业	材料加工工程
关键词	高氮无镍不锈钢冠状动脉支架有限元 High Nitrogen Nickel-free Austenitic Stainless Steel Coronary Stent Finite Element Method
摘要	"目前临床上常用的冠状动脉金属支架通常采用316L不锈钢和钴铬镍合金（L605）加工而成，其中采用高强度的L605合金制作的精细网丝支架，可以降低对血管内膜的刺激，从结构上减少了支架内再狭窄的潜在诱因，已经成为新型冠脉支架发展的趋势。具有高强度和优良生物相容性的高氮无镍奥氏体不锈钢是一种有潜力的冠状动脉支架用不锈钢新材料，采用高氮无镍奥氏体不锈钢不仅可以加工出与L605合金一样的精细网丝的新型冠状动脉支架，同时又可以避免临床应用的316L不锈钢和L605合金支架中镍溶出对镍过敏患者的术后再狭窄和并发症。本论文针对课题组开发的高氮无镍不锈钢新材料，对比临床上广泛使用的316L不锈钢和L605合金，采用有限元分析方法对目前常用的支撑筋+连接筋的冠状动脉支架进行了紧缩回弹、扩张后的弹性回复和轴向短缩、径向支撑强度及柔顺性等力学行为的模拟研究，得到如下主要研究结果： 1. 相同条件下，316L不锈钢支架由于屈服强度低其紧缩回弹最小，而高强度的无镍不锈钢和L605合金支架的紧缩回弹较大；随着支架的筋宽和壁厚减小，支架的紧缩回弹逐渐增大；紧缩量对支架的紧缩回弹量影响较小；随支架的支撑筋长度和支撑筋端部中心曲率半径的增加，支架的紧缩回弹均有较大程度地增加。 2. 在支架扩张过程中，支架材料及尺寸等因素对支架弹性回复的影响规律与对其紧缩回弹的影响规律基本一致。支架的轴向短缩对支架材料的变化及支架筋尺寸的变化都不敏感；支架的轴向短缩与支架的扩张程度以及支架的结构有关，随支架扩张程度的增大以及支架的支撑筋长度和支撑筋端部中心曲率半径的减小而逐渐增大。 3. 相同条件下的无镍不锈钢支架和L605合金支架的径向支撑强度相差不大，均明显高于316L不锈钢支架；支架的径向支撑强度随着支架筋尺寸增大而明显提高，支架筋宽比其壁厚更显著地影响支架的径向支撑强度；随着支架扩张程度的增加，支架的径向支撑强度有小幅度的增加；随着支架支撑筋长度和支撑筋端部中心曲率半径的增加，支架的径向支撑强度均有相当明显的降低。 4. 相同条件下的L605合金支架的柔顺性较低，无镍不锈钢支架和316L不锈钢支架的柔顺性相当；支架的柔顺性随着支架的筋宽和壁厚的减小而逐渐提高，同样支架的筋宽比壁厚更显著地影响支架的柔顺性；另外，支架设计时，可以在不改变支架的支撑筋特征、保证支架的径向支撑强度的前提下，通过改变连接筋的尺寸、形状和个数等方法来改善支架的柔顺性。综上所述，高氮无镍不锈钢新材料可以利用其高强度加工成网丝细小的冠状动脉支架，获得与L605合金支架相近的径向支撑强度以及更优良的柔顺性。高强度的高氮无镍不锈钢支架和L605合金支架相对于316L不锈钢支架较高的径向和轴向回弹，可以通过优化支架结构设计来改善，并在支架应用过程中可通过过紧缩和过扩张来避免其弊端。 "
其他摘要	"At present, the clinical coronary stents are commonly made by 316L stainless steel and Co-Cr-Ni alloy (L605). The fine mesh stent made of high-strength L605 alloy, which can reduce the stimulation to the intima, has become a developing trend of new coronary stent. The high nitrogen nickel-free austenitic stainless steel which has high strength and excellent biocompatibility is a potential new coronary stent material. The stent made of high nitrogen nickel-free austenitic stainless steel can not only process the fine mesh as L605 alloy but also avoid the restenosis caused by the nickel allergy while using the stent made of 316L stainless steel or L605 alloy. In this study, the finite element method was applied to contrastively analyse the mechanical behaviors such as the recoil after crimping, the recoil and shortening after expansion, the radial strength and the flexibility of the stents made of high nitrogen nickel-free austenitic stainless steel, and the widely used 316L stainless steel and L605 alloy. The main conclusions have been made as follows: 1. In the crimping process, the reciol of 316L stainless steel stent is smallest for its low yield strength, while the recoils of the stents made of high strength nickel-free austenitic stainless steel and L605 alloy are larger; with decrease of the strut width and thickness, the reciol of the stent is increased; the crimped scale of stent has little influence on the recoil of stent; with increase of the length and curvature of the strut, the reciol of the stent is increased. 2. In the process of stent expansion, the influences of the stent material and other factors on the stent recoil are consistent with that in the crimping process. The stent shortening after expansion is not sensitive to the stent material and the width and thickness of the stent; with increase of the expansion scale and decrease of the length and curvature of the strut, the stent shortening after expansion is increased. 3. Under the same conditions, the stents made by nickel-free austenitic stainless steel and L605 alloy have similar radial strength, which is significantly higher than that of the 316L stainless steel stent; with increase of the strut width and thickness, the radial strength of the stent is increased obviously; with increase of the the expansion scale, the radial strength of the stent is increased slightly; with increase of the length and curvature of the strut, the radial strength of the stent is decreased obviously. 4. Under the same conditons, the flexibilities of nickel-free austenitic stainless steel stent and 316L stainless steel stent are basically equal, which is significantly better than the L605 alloy stent; the flexibility of stent is significantly decreased with increase of the strut width and thickness; in addition, decreasing the width and numbers of the stent link, and improving the shape of the stent link can also improve the flexibiity of the stent. In conclusion, using the high nitrogen nickel-free austenitic stainless steel can make fine mesh stent which has high radial strength as L605 alloy stent and better flexibility; the high reciol of the stent made of high nitrogen nickel-free austenitic stainless and L605 alloy can be improved by optimizing the stent design or avoided by over-crimping and over-expanding."
文献类型	学位论文
条目标识符	http://ir.imr.ac.cn/handle/321006/64506
专题	中国科学院金属研究所
推荐引用方式 GB/T 7714	刘凤. 高氮无镍不锈钢冠奖动脉支架力学行为的有限元研究[D]. 北京. 中国科学院金属研究所,2012.