不同应力水平对支架降解影响的有限元分析  

Finite element analysis of the effect of different stress levels on the degradation of the stent

作　　者：张晗冰 杜田明 张艳萍[1] 陈诗亮 刘圣文 乔爱科[1] ZHANG Hanbing;DU Tianming;ZHANG Yanping;CHEN Shiliang;LIU Shengwen;QIAO Aike(Faculty of Environment and Life,Beijing University of Technology,Beijing 100124;Department of Cardiology,Fuwai Hospital,Chinese Academy of Medical Sciences,Beijing 100032)

机构地区：[1]北京工业大学环境与生命学部,北京100124 [2]中国医学科学院阜外医院心内科,北京100032

出　　处：《北京生物医学工程》2024年第3期229-235,241,共8页Beijing Biomedical Engineering

基　　金：国家自然科学基金(12172018);北京市教委-市自然基金联合项目(KZ202110005004)资助。

摘　　要：目的建立多种腐蚀因素共同作用的支架降解模型,探究不同应力水平对可降解支架的降解行为及服役性能的影响。方法基于连续损伤力学原理,通过在有限元框架下为独立单元设置腐蚀属性和材料属性,对支架降解过程中的力学强度和几何变化进行模拟,由此建立均匀腐蚀、应力腐蚀及点腐蚀多种因素共同作用下的支架动态降解模型。分别将支架扩张至血管直径的1.05、1.1、1.2倍为支架提供不同的应力水平,对三种不同工况的降解过程进行数值模拟,分析降解过程中的支架形态、质量损失率及服役时间等。结果支架植入后的应力水平会对其服役性能产生显著影响。随着扩张比的增加,三种应力水平下支架断裂的时间分数分别为0.95、0.82和0.78,断裂时的质量损失率分别为73%、63%和60%。降解过程中由应力腐蚀主导移除的单元数量分别为112、125和139;应力腐蚀作为主导因素的时间分数分别为0.93、0.82和0.78。血管塌陷的时间分数分别为0.83、0.72和0.68,并且血管塌陷发生在支架失去其几何完整性之前。结论对于可降解支架,选择恰当的扩张比对获得良好的支架治疗效果有重要影响。高扩张比在更好维持管腔通畅性的同时也通过提高花冠处的应力水平使局部应力腐蚀作用增加,从而缩短了支架的服役时间,导致其更容易发生不均匀降解。Objective Establish a stent degradation model with multiple factors to explore the effects of different stress levels on degradable vascular stents'degradation behavior and degradation performance.Methods Based on the continuous damage mechanics principle,the stents'mechanical strength and geometric changes in the degradation were simulated by setting corrosion properties and material properties for the independent elements under the finite element framework,then a stent degradation model of uniform corrosion,stress corrosion,and pitting corrosion was established.The stent was expanded to 1.05,1.1,and 1.2 times the vessel diameter,respectively,to provide different stress levels for the stent,and the degradation process under three different conditions was numerically simulated.The stents'shape,mass loss rate,and time during degradation were analyzed.Results The stress level of stents after deployment significantly affects its degradation performance with the increase of expansion ratio,the fracture time of the stent under three stress levels was 0.95,0.82,and 0.78,and the mass loss rate at fracture was 73%,63%,and 60%.During the degradation,the number of elements removed mainly by stress corrosion was 112,125,and 139,respectively,and the fraction of stress corrosion as the dominant factor time was 0.93,0.82,and 0.78,respectively.The fraction of vascular collapse time was 0.83,0.72,and 0.68,respectively.Vascular collapse occurs before the stent loses its mechanical integrity.Conclusions Choosing an appropriate expansion ratio for biodegradable stents have a significant impact on the well treatment effect.Although a high expansion ratio could better maintain lumen patency,it also increases local stress corrosion by increasing the stress level at the corolla,thereby shortening the degradation time of the stent and making it more prone to non-uniform degradation.

关 键 词：可降解支架 植入扩张比 应力腐蚀 支撑性 有限元分析 

分 类 号：R318.01[医药卫生—生物医学工程]