【作者】 黄河；

【导师】 任露泉；

【作者基本信息】 吉林大学 ， 仿生科学与工程， 2012， 博士

【摘要】 冲蚀磨损是工程表面不断受到含有微小体积粒子的流体冲击，表面材料出现损失的一种磨损现象。固体粒子冲蚀磨损会导致工程表面或机械零部件的寿命低于设计指标，带来经济损失，如：修复、维护、替换被磨损的工件均会带来时间和资金成本增加，导致生产效率下降，而且还会直接导致能耗的增加，加重环境负担。为适应风沙夹带固体粒子的冲蚀环境，沙漠蜥蜴背侧体表进化出优异的生物功能，对冲蚀磨损具有很强的耐受能力。研究沙漠蜥蜴耐冲蚀磨损机理可为新型耐冲蚀磨损表面的设计提供仿生学依据，具有重要的理论价值和应用前景。本论文以仿生学理论与生物耦合理论作为理论依据，选取沙漠蜥蜴作为生物原型，基于其体表实现耐冲蚀磨损功能的生物耦合特性，设计仿生样件，利用试验、模拟、和理论分析的方法，研究仿生样件的耐冲蚀磨损机理，分析沙漠蜥蜴耐冲蚀功能实现模式。本文使用体视显微镜、三维激光扫描技术、皮肤切片染色技术，对沙漠蜥蜴体表典型耐冲蚀部位体表形态特征与表皮结构进行了分析，对沙漠蜥蜴体表耐冲蚀功能产生原因进行了探讨。分析表明：沙漠蜥蜴体表由构型、尺寸、形状不一的鳞片通过不同的排列方式构成；其体表鳞片主要为四边形、六边形、菱形，鳞片中部均有不同程度的突起；鳞片间紧密排列，并以一定排列方式形成横向或纵向的沟槽；每个鳞片由外部较硬的β-角质层和内部具有生物柔性的α-角质层、结缔组织层组成，形成一种壳复合结构；体表材料则可看做由多层力学特性不同的材料复合而成。这种形态、结构、材料相耦合使沙漠蜥蜴体表具有优异的耐受固体粒子冲蚀的功能。通过对沙漠蜥蜴耦合特征规律与机制进行分析，确定沙漠蜥蜴体表形态与皮肤结构均属于耦元，且均为显性、永固、静态耦元。耦元间的耦联关系是静态的、紧密的。耦元间在系统中以叠加关系有机组合，沙漠蜥蜴体表耐冲蚀功能的实现模式是“完全均衡并行实现”。本文根据沙漠蜥蜴体表三维形貌设计了沟槽形态仿生样件；根据背侧皮肤组织结构设计了结构仿生样件；结合形态与结构特征，设计了形态-结构耦合样件。使用冲蚀磨损试验机对仿生样件进行了固体粒子冲蚀试验。试验结果表明：与普通样件相比，形态仿生样件的耐冲蚀性能最多可以提高约20%；结构仿生样件的耐冲蚀性能可以提高约10%。使用回归优化设计的方法建立了形态-结构耦合仿生样件的冲蚀磨损回归模型。使用粒子冲击试验、LS-DYNA碰撞分析，FLUENT流场分析等方法对结构仿生样件和形态仿生样件的耐冲蚀磨损机理进行分析。以能量守恒原理、弹性碰撞理论、冲蚀磨损理论作为基础，建模分析结构因素对耐冲蚀磨损性能的影响。基于临界速度理论，分析了粒子速度与靶材损伤间的数学关系。结果表明：沟槽形态可以增加边界层内扰动，使气流更容易产生拟序结构，形成湍流，降低了粒子碰撞壁面的几率；沟槽形态还可以导致近壁流内形成垂直于表面向上的速度矢量，从而减缓了固体粒子的法向冲击速度。本文采用的复合材料形成层状结构，具有刚性强化和柔性吸收特点，可有效吸收粒子冲击产生的法向应力，并能缓释切向应力，阻碍表面应力出现过度集中，改善了材料表面的应力分布状况。在模拟试验和实际试验结果的基础上，确定了沙漠蜥蜴耦生物耦合的主元为形态耦元，次主元为结构耦元。全文共分八章。第一章对固体冲蚀磨损的产生机理与影响因素进行了介绍，并对固体粒子冲蚀磨损研究进展进行了综述。第二章根据沙漠蜥蜴的生物耦合特性分别设计了形态仿生样件、结构仿生样件、耦合仿生样件，并在第三、四、五章分别对其进行了冲蚀磨损试验。第六章对5种材料进行了冲蚀磨损试验，分析了冲蚀条件对冲蚀磨损的影响。第七章以冲蚀磨损试验结果为依据，分别讨论了形态因素、结构因素对样件冲蚀磨损特性的影响，并利用单粒子冲击试验、LS-DYNA碰撞模拟、FLUENT流场模拟对仿生样件的耐冲蚀机理进行了分析，得出了沙漠蜥蜴的生物耦合特征与机制。第八章为本文结论。更多还原

【Abstract】 Erosion is the process of losing surface material which happens when smallparticle entrained by fluid continuously impinging on engineering surface. The solidparticle erosion can cause lifetime reduction of engineering surfaces or mechanicalcomponents, which lead to economic losses. For example, repairing, maintaining,replacing the worn-out components not only can lead to the increase of time and cost,the decrease of production efficiency, but also can cause the increase of energyconsumption and the burden of the environment. In order to adapt to the particleserosion environment, the desert lizards have evolved excellent biological function,in which their dorsal surfaces have good resistance to the solid particle erosion. Theresearches on the anti-erosion mechanism of desert lizards can provide the basis forthe design of novel erosion-resistant surface, and have important theoretical valueand application prospect. In this paper, according to the bionics theory andbiological coupling theory, the desert lizards were selected as biological prototype.On the basis of the biological coupling characteristics of desert lizards’erosion-resistant function, the bionic samples were designed and fabricated, and theanti-erosion mechanism and implementation patterns of bionic samples were studiedby using experiments, simulation and theoretical analysis.The surface morphological characteristics and skin structures of typical parts ofthe desert lizard dorsal’s skin which has erosion-resistance function were analyzedusing the stereo microscope,3D laser scanning technology, and skin biopsy stainingtechnique, respectively. The anti-erosion mechanism of the desert lizard’s dorsalskin was analysed and discussed. The results showed that the dorsal surface of desertlizard was composed by the various scales which have different configuration, size,and shape. The shape of scales can be classified into quadrilateral, hexagon, and diamond. There is certain degree of bulge on the middle part of scale. The scales arearranged compactly which forms transverse or longitudinal grooves. Each scaleconsists of outer layer and inner layer that are respectively made by rigid β-cuticleand elastic α-cuticle and connective tissue, which forms a shell composite structure.The dorsal skin of desert lizard can be regard as a laminated composites materialwhich composed by multilayer materials with different mechanical properties. Bycoupling the morphological and structural characteristics, the dorsal surface ofdesert lizard has excellent property of solid particle erosion resistance. As thecoupling characteristic and mechanisms of desert lizard were analysed, the all thecoupling elements were determined as dominant, permanent, and static couplingelement. The coupling relationship between the elements is static and close. In thecoupling system, integrated mode of elements is superposition. The implementationpattern of desert lizard’s erosion resistance function is completely balanced parallelimplementation.The morphological bionic samples were designed based on thethree-dimensional shape of dorsal surface of desert lizard; the structural bionicsamples were designed according to the skin tissue structure; the coupling bionicsamples were designed by synthesizing the morphological and structuralcharacteristics. The solid particle erosion experiments were carried out using particleerosion test facility. The experimental results showed that the erosion resistanceperformance of morphology bionic samples has increased20%by comparing withcommon samples, and increased10%for structural samples. The regression modelof morphology-structural coupling bionic sample was established by regressionoptimization design. The erosion resistance mechanism of morphological andstructural bionic samples was analyzed using particle impacting test, LS-DYNAimpact simulation, and FLUENT flow field numerical simulation, respectively. Theeffect of structural factor on particle erosion resistance was analyzed with the basisof energy conservation law, the elastic collision theory, and erosive wear theory.Based on the critical velocity theory, the mathematical relationship between theparticle velocity and target material damage was established. The results show thatthe grooved surface can increase the disturbance in boundary layer, easily form thecoherent structures, which easily turn the laminar flow into turbulent one. Therefore, the probability of particle impinging the target material surface was reduced.Moreover, the grooved surface can also cause the formation upward velocity vector,which is perpendicular to the surface, in the near-wall flow filed, thereby slowingthe speed of the solid particles before impinging. The structure formed by laminatedcomposites materials has the characteristics of rigid strengthening and flexibilityabsorption, which can effectively absorb the normal stress generated by the particleimpact, sustained-release tangential stress, obstruct the excessive concentration ofsurface stress, and improve stress distribution on the material surface. Based on theresults of simulation and experiments, importance degree of coupling elements wasanalyzed. The results show that the main element of desert lizard’s biologicalcoupling is morphology factor, and the secondary element is structure factor.The paper consists of eight chapters. In the Chapter I, the mechanism of solidparticle erosion and influencing factors were presented, in which the researchprogress on solid particle erosion were reviewed. The morphological, structural andbionic coupling samples for erosion experiments were designed in the Chapter II,and tested in the Chapter III, IV and V, respectively. In the Chapter VI, the erosionproperties of five kinds of materials were tested by solid particle erosionexperiments, and the effect of experimental conditions on the erosive wear wasanalyzed. Base on the erosive wear test results, the effect of morphological,structural factors on erosive wear characteristics of samples were discussed in theChapter VII. Besides, the particle impacting test, the LS-DYNA impact simulation,and FLUENT the flow field simulation were adopt to analyze the erosion resistancemechanism of bionic samples, and analyze the mechanisms of desert lizards’biological coupling characteristics. In the Chapter VIII, the conclusion of this paperwas drawn.更多还原