【作者】 龙东平；

【导师】 谭建平；

【作者基本信息】 中南大学 ， 机械设计及理论， 2008， 博士

【摘要】 人工心脏、人工心肺机等人工器官的研制和使用过程中机械部件的磨损严重影响着其寿命和可靠性,良好的润滑不仅可以减小人工器官的磨损,延长其使用寿命,还可以保证病人的生命安全,提高生活质量。利用患者自身血液作为这类人工器官的润滑剂,可解决上述难题。血液是具有生理活性的流体,其组分复杂,流动性特殊,这就使得血液润滑带来优越性的同时也带来了一定的难度,加之以往对血液的研究主要集中在生理和病理等临床医学领域,将其作为机械部件的润滑剂是前人所未作过的尝试性探索研究。在血液流变学的基础上,探讨血液的各理化指标,结合血液的特殊流变性,利用线性粘弹性模型—Maxwell流变模型来描述血液的宏观的非牛顿流体特征和血细胞的微观粘弹性特征。在此模型的基础上,从微观和宏观两个方面对血液的润滑特性进行研究。本文针对血液的特殊性,分析讨论了影响血液润滑的因素—红细胞的聚集、变形、组分变化、摩擦界面的表面性能及温度变化等因素。针对血液润滑的特殊性,提出了评价血润滑性能的判定指标:(1)生物相容的指标—血栓;(2)生理限制的指标—溶血;(3)反映润滑性能的能承载能力;(4)温度限制。材料的表面性能决定了血细胞在摩擦界面的吸附特征及润滑过程中的表现。血细胞在材料表面的吸附会对血液的润滑性能产生影响。本文利用原子力显微镜研究了吸附在钛合金表面和云母表面的红细胞形态变化。从微观细胞力学的角度探讨在润滑过程血细胞的吸附特性和微观力学行为,在细胞力学的基础上建立了血细胞的粘附模型。基于所建立的粘附模型,从微摩擦的角度探讨血细胞的微摩擦机理,首次利用原子力显微镜研究生物细胞表面的微摩擦力及摩擦系数,从微观上研究血液的润滑提供了条件。针对血液粘弹性的特征,从分析血液组分出发,研究了红细胞比积的变化对血液粘弹性及润滑性能的影响,对不同红细胞比积的血液的承载能力进行了实验研究,发现红细胞的比积大小影响着血液的承载能力,红细胞比积越大,血液的承载能力越强。结合宏观摩擦实验,对原来建立的血液宏观粘弹性模型进行了修正,并在此基础上建立了红细胞比积和血液承载能力的关系模型;结合血液组分的动态变化和润滑间隙的动态变化,研究了血液润滑状态的变化,针对不同的血液润滑状态建立了血液润滑状态模型。推导了基于血液宏观Maxwell粘弹性模型的雷诺方程,并将此雷诺方程应用于微型轴流式血泵的仿真分析,得出了相应结论,为进一步研究血液的润滑和血泵结构的优化提供了基础。更多还原

【Abstract】 The wearing abrasion of the research and use of artificial organ mechanical parts, Such as mechanical heart and heart-lung machine, badly affects their longevity and reliability. Favorable lubrication can not only reduce abrasion of the artificial organs, but also guarantee the patient’s life safety and improve the life quality. Using the patient’s blood as the friction lubricant between the movement parts is an effective way to solve the difficult problem. Blood is a physiological activity fluid, with its complex components and special fluidity,which brings advantage and disadvantage effect of the blood lubrication. Besides, researchers principally concentrated their blood researches on the clinical medicine domain formerly, such as physiology and pathology and so on. There are very few predecessors in literature who attempted to explore the blood lubricating as mechanical parts lubricant.Based on blood hemorheology theory, several physiological and biochemical indexes of the blood were discussed in this paper. Considered the special properties, the linear viscoelastic model of Maxwell Model was used to describe non-newtonian fluid properities of blood in macrocosmic and microcosmic viscoelastic of blood cell. Based on the Maxwell model, the lubricating properties were investigated both from macrocosmic and microcosmic aspects.According to special properties of blood, these factors including deformation,aggregation of blood cell, the component variation, properties of friction interfacial, temperature and so on, these affect the lubricating properties of blood were investigated. According to special lubricating properties of blood, on basis of those factors, a framework of blood lubrication evaluation indexes are proposed:(1)the biological compatibility indicators of the friction interface—thrombus;(2)the biological restrictions indicators—hemolysis;(3)the loading and bearing capacity confine which is evaluation the lubricant;(4)the temperature of the interfacial friction is confined in the range of body temperature of human. The adsorption characters and morpholgy of blood cell and the lubrication properties were decided by the surface properties. The adsorption of blood cell on the surface can affect the lubrication performance. The AFM, in this paper, was used to research the microcosmic morphology and mechanical characters of blood cells, which were absorded on surface Ti alloy and mica. The absorption properties and micromechanical behaviors were investigated from the aspect of micromechanics. Based on the cellar mechanics, the absorption model of blood was build too. On basis of micro-tribology, the micro-friction mechanism of blood cell’s suface was discussed. For the first time,the friction force and friction coefficient of blood cell’s surface were investigated, and then the principle of friction on the surface of biological cells were researched by AFM. All of these works lay the foundation for improving the blood lubrication effect and decreasing the damage for blood cell.From the viscoelastic characteristics of the blood to the analysis of blood components, the experimental results show that the blood cell hematocrit influences the blood mechanical loading capacity. That is, the greater hematocrit is, the stronger blood loading capacity is. Through macro-friction experiment, the original established macro viscoelastic models of the blood are amended. On the basis of these, relational models between hematocrit of the blood red cells and blood loading capacity are set up. With the dynamic change of blood components and the dynamics of lubrication gap, lubrication state change of the blood lubrication was researched. In view of the blood lubrication, under different lubrication case, different blood lubrication state models were also established.Based on this, Reynolds equations suitable for Maxwell equation were deduced, and then the Reynolds equations were applied to the emulation analysis in the minimal axial blood pump. The corresponding conclusions drawn will provide a basis for further studying the blood lubricating and the optimization of the blood pump structure.更多还原