生物瓣膜几何设计理论及其有限元分析

Geometry design theory and finite element analysis of bioprosthetic heart valve

文章以薄膜理论为依据,以有限元方法为手段,以接近或达到人体心瓣的力学性能为目的,对生物瓣膜的几何设计方法进行详尽的理论分析并对不同形状的瓣叶应力分布情况进行了比较。利用传统设计理论和现代设计方法相结合,参照心瓣瓣叶参考型面选择符合条件的圆球面和圆柱面,构建能够达到人体心瓣功能的人工生物瓣几何参数化模型。随之对二者应力的分布进行分析。从而实现利用计算机辅助设计得到心瓣几何造型模型参数,并对其进行有限元分析的方法。结果表明:其分析结果与理论分析具有一致性,即球体型面瓣叶应力分布较为合理,最大应力区远离接缝部位,最大主应力值也较小;柱面型的瓣叶在接缝部位表现出较大的应力集中,且在整个瓣叶范围内分布极不均匀合理。通过对两种型面的应力分析可以看出球面型瓣叶的力学性能要明显优于柱面型的瓣叶。同时,将生物瓣瓣叶材料简化为拟线弹性材料时,对瓣叶应力分布的影响不大,计算结果差异在一定可接受范围内。该结果为生物瓣膜的设计、制作提供坚实的理论基础。

This paper analyzes the bioprosthetic heart valve＇s geometry design method and compares the stress distribution of the different shape leaflets based on the membrane theory and finite element analysis method in order to maximally reach the mechanics performance of human being＇s heart valve. According to both traditional design theories and modern design method, we choose the sphere and cylinder surfaces as valvular leaflets referenced frame and build the geometrical parametric model to analyze the stress distribution. After constructing parametric models of bioprosthetic heart valves via computer-aided design, a series of accurate dimension parameters are obtained to perform finite element analysis. The results indicate that force distribution of sphere valves leaflets is reasonable. The peak stress of sphere valve leaflets is comparatively far from seam position, and the maximal primary stress of sphere valve leaflets is less than that of cylindrical valves leaflets. It is also found that cylindrical valves leaflets have such obvious features as concentration of stress and non-uniform force distribution. Therefore, performance of sphere valves leaflets is superior to that of cylindrical valves leaflets. Meanwhile, it also indicates that the situation of stress distribution is not influenced obviously by the hyper-elasticity material of leaflets simplifying to imitative linear elastic material, but there is a certain tolerance. The present result provides a theoretical guide and useful information for the bioprosthetic heart valve designer.