基子流固耦合生物瓣膜非线性力学性能分析

发布时间：2018-06-16 20:15

本文选题：生物瓣膜 + 计算机辅助设计　；参考：《山东大学》2015年硕士论文

【摘要】：心脏是为人体血液循环提供必要动力的装置,而心脏瓣膜是保证血液按一定方向流动的控制原件。在一个心动周期中,瓣叶要经历复杂的形变以及流过瓣膜的血液量也很高,这使得瓣膜易发生病变。目前有效治疗瓣膜疾病的手段为心脏瓣膜置换术。生物瓣膜与天然心脏瓣膜相似,流场特性接近天然心脏瓣膜,具有较好的血流动力学性能,不需要终身服用抗凝药物,造成血栓栓塞的几率低等优点,但患者置换心脏瓣膜后,由于生物瓣膜的钙化和撕裂使心脏瓣膜损坏从而降低瓣膜的使用寿命,提高生物瓣膜的耐久性是生物瓣膜研究领域亟待解决的问题。本文以心脏流体力学为理论依据,根据生物瓣膜的设计原则,对生物瓣膜进行参数化设计,运用三维建模软件构建了瓣膜瓣叶及动脉壁的三维实体模型。在有限元软件中构建生物瓣膜与血液的流固耦合模型,针对不同瓣叶材料特性、不同瓣叶型面以及不同瓣叶厚度的生物瓣膜进行流固耦合动力学模拟,分析对比几种不同参数对生物瓣膜力学性能的影响,为进一步设计性能优良的生物瓣膜提供理论基础。本文利用计算机软件对生物瓣膜在不同参数下进行动力学模拟分析。分析结果表明,不同材料特性的瓣叶,其应力分布基本相同,但非线性材料瓣叶的应力最大值略高于线性材料瓣叶。应力集中区域均主要位于结合边与缝合边的交界处,非线性材料瓣叶应力集中更明显,在结合边与缝合边交界处的等值线较为密集,这更加贴近瓣叶真实的应力分布情况；四种型面瓣叶都出现了不同程度的应力分布不均匀现象,应力集中区域略有不同。圆柱面在各方面的力学性能均较差,而旋转抛物面、圆球面和椭球面在不同方面有着各自的优势；圆球型面与旋转抛物型面瓣叶的厚度分别为0.45mm与0.4mm时具有较好的动态力学性能。本文以天然心脏瓣膜相关理论为依据,利用有限元软件针对生物瓣膜进行流固耦合动力学模拟,分析不同参数下的瓣膜动态力学性能的影响,并对它们进行分析对比,从而进一步优化瓣膜的力学性能,为提高生物瓣的耐久性提供了可靠依据。
[Abstract]:The heart is a device that provides the necessary power for the circulation of human blood, and the heart valve is the control element to ensure the blood flow in a certain direction. In a cardiac cycle, the valve leaves undergo complex deformation and high blood flow through the valve, which makes the valve prone to pathological changes. Valvular replacement is the effective treatment of valvular disease. The biological valve is similar to the natural heart valve, the flow field characteristic is close to the natural heart valve, has the good hemodynamic performance, does not need to take the anticoagulant drug for life, causes the thromboembolism probability and so on low, but after the patient replacement heart valve, Because of the calcification and tear of biological valve, the damage of heart valve can reduce the service life of valve, and improve the durability of biological valve is an urgent problem to be solved in the field of biological valve research. Based on the theory of cardiac fluid mechanics and according to the design principle of biological valve, the parameterized design of biological valve was carried out in this paper, and the three-dimensional solid model of valve lobe and arterial wall was constructed by using three-dimensional modeling software. The fluid-solid coupling model of biological valve and blood was constructed in finite element software. The fluid-solid coupling dynamics of biological valve with different valve material characteristics, different valve leaf profile and different leaf thickness were simulated. The effects of different parameters on the mechanical properties of biological valves are analyzed and compared to provide a theoretical basis for the further design of biological valves with excellent performance. In this paper, a computer software is used to simulate the dynamics of biological valves under different parameters. The results show that the stress distribution of the leaves with different material characteristics is basically the same, but the maximum stress of the nonlinear material leaves is slightly higher than that of the linear ones. The stress concentration region is mainly located at the junction between the combined edge and the suture edge, and the stress concentration of the nonlinear material flap is more obvious, and the isoline at the junction between the combined edge and the suture edge is more dense, which is closer to the true stress distribution of the lobe. The stress distribution was uneven in all the four types of flaps, and the stress concentration region was slightly different. The mechanical properties of the cylindrical surface are poor in all aspects, while the rotating paraboloid, the spherical surface and the ellipsoidal surface have their own advantages in different aspects. When the thickness of spherical and rotating parabolic lobes is 0.45mm and 0.4mm, respectively, they have better dynamic mechanical properties. Based on the theory of natural heart valve, the fluid-solid coupling dynamics of biological valve was simulated by finite element software. The effects of different parameters on the dynamic mechanical properties of the valve were analyzed and compared. Thus, the mechanical properties of the valves are further optimized, which provides a reliable basis for improving the durability of the biological valves.
【学位授予单位】：山东大学
【学位级别】：硕士
【学位授予年份】：2015
【分类号】：R654.2

【参考文献】