新型可降解金属血管支架的有限元力学分析

近年来,镁合金血管支架被用于动物实验和临床研究.文献中报道,镁合金支架具有良好的生物相容性,植入血管后能够被逐渐腐蚀降解,但与不锈钢相比,镁合金材料脆性大,塑性变形能力差.根据Biotronik公司的两种镁合金血管支架建立有限元模型.有限元分析结果表明,扩张过程中支架中的最大应变达到20%,超过了目前市场上提供的镁合金的最大延伸率.因此,为了研制出可用的镁合金血管支架,需要优化设计血管支架的几何形状,避免应力集中,同时需要定制镁合金成分,并通过细化晶粒,提高材料的塑性变形能力.

Mechanical Analysis of New Type Biodegradable Metal Stents Based on FEM

Magnesium-alloy stents have been employed in animal experiments and clinical researches in recent years. It has been reported to be biocompatible, and degradable due to corrosion after being implanted into blood vessel. However, magnesium alloys is relatively brittle compared with stainless steel and the stent strut made of magnesium alloys may break under large deformation. In this paper, models of two magnesium-alloy stents were set up with reference to pictures from Biotronik Corporation. Results of the finite element analysis show the maximum strain during expanding reaches 20% , greater than the strain limit of commercially available magnesium alloys. Therefore, in order to develop practicable magnesium-alloy stents, the stent shape needs to be optimized to avoid stress concentration; the magnesium alloys should be custom-made and treated with grain refinement processes to improve its plastic deformation property.