不锈钢冠脉支架耦合扩张变形生物力学性能的模拟研究

Simulation studies on the biomechanical performances of coronary stainless steel stents in coupling expansion

利用非线性有限元方法仿真模拟不锈钢(SUS-316L)3种不同结构冠脉支架动静态耦合扩张过程和生物力学性能。研究支架在压握收缩、自由扩张、卸载过程以及脉流循环变应力持续作用过程中有限元模型的网格划分、材料本构模型建立、边界条件、载荷定义和接触处理等关键技术。根据有限元计算结果得到了3种支架在耦合扩张过程中最大等效应力为807.9MPa,最大塑性应变为0.208;3种支架的轴向缩短率、径向反弹率、扩张不均匀性都在13%以内,静态安全系数>1.3,动态安全系数>1.1;并与实验测试数据进行分析比较,理论分析与体外扩张实验结果吻合较好,误差在7%以内,验证了有限元模拟的准确性和合理性。本文的模拟方法为冠脉支架的优化设计、新产品开发以及临床评估提供了科学的依据。

The dynamic-static coupling expansion process and biomechanical properties for three kinds of stain-less steel （SUS-316L）coronary stents were investigated using nonlinear finite element method.The key tech-nologies such as meshing,material constitutive model,boundary conditions,loading definition and contact in-teraction,were discussed in detail,as the stent underwent the crimp induced-contraction,free expansion,un-loading and continuous pulsation circulating stresses.According to finite element analysis （FEA）results,dur-ing the coupling expansion of stents,the maximum equivalent stress was 807.9 MPa,and the maximum plastic strain was 0.208;the axial shortening rate,radial bounce rate and expanding nonuniformity of three stents were all within 1 3%,while the static safety factor was over 1 .3 ,and the dynamic safety factor was over 1 .1 .The numerical results agreed well with experimental data and the error was less than 7%,strongly demonstrating the rationality and validity of FEA results.The proposed simulation method provides a scientific basis for the optimization and clinical evaluation of the coronary stents.