【作者】 田喜梅；

【导师】 任露泉；

【作者基本信息】 吉林大学 ， 仿生科学与工程， 2013， 博士

【摘要】 磨损是指相互接触的物体在相对运动过程中，表层材料不断损失、转移或产生残余变形，并最终导致材料破坏或设备失效的现象，其广泛存在于众多工程领域。据统计，约有80%的机械零部件由于磨损而失效，约30-50%的世界一次能源由摩擦磨损所消耗。磨损不仅消耗材料，浪费能源，并直接影响到机械器件的寿命和可靠性。因此，减摩抗磨问题已成为众多工程领域研究的热点与难点，越来越得到国内外高度重视。大自然为我们提供了优异的生物耐磨仿生蓝本，这些生物体为适应生存环境和满足生存需要，进化出形态、结构与组成材料等多因素耦合的生物耐磨功能系统，体现出对生存环境最佳的适应性和协调性。本文以具有良好耐磨特性的典型贝类壳体为研究对象，运用耦合仿生理念，从形态、结构与材料多个角度入手，深入探索其生物耐磨耦合机制，从而为开发新型仿生耐磨器件提供重要信息，同时为完善耦合仿生理论提供基础资料。作为一种典型的天然生物矿化材料，贝壳的构成具有令人佩服的特殊的组装方式，体现出强韧性的最佳匹配。此外，贝壳通常具有多种复杂的体表形貌，表现出良好的耐磨料磨损和抗冲蚀磨损特性。本文以分别营埋栖、底栖匍匐和附着匍匐三种不同生活方式的典型贝类毛蚶（Scapharca subcrenata）、脉红螺（Rapana venosa）和石鳖（Acanthochiton rubrolineatus）为研究对象，通过多种试验手段分别对其生物学特性、力学特性和磨损特性进行了系统的研究；并利用ANSYS大型通用有限元软件，分别对基于毛蚶与石鳖壳体的单元仿生模型及耦合仿生模型的磨料磨损及冲蚀磨损过程进行了三维数值模拟分析，初步揭示了典型贝类壳体生物耦合耐磨特征机制与规律。在生物耦合特征分析中，借助体视显微镜、扫描电镜及X射线衍射仪分别对三种贝壳的表面形貌、微观结构及组成材料进行了系统研究。结果表明，毛蚶壳体具有复杂的表面形貌，在左壳表面存在放射肋与小结节组成的复合结构；且在三种贝壳微观结构中普遍存在具有应力缓释效应的交叉叠片结构以及孔状管道结构。显微硬度试验结果表明，贝壳的显微硬度与其对应的微观结构密切相关，且存在各向异性。毛蚶次表层即棱柱层与脉红螺珍珠层的交叉叠片结构硬度最高，石鳖珍珠层的复杂交叉条纹结构也表现出相对较高的显微硬度，说明交叉纹片结构是贝壳抵抗外力破坏的一种有效晶体结构。压缩试验结果表明，贝壳层面方向的承载能力均高于横断面的承载能力，且压缩强度与对应的微观结构同样具有相关性。在磨损试验研究中，采用分离耦元试验法及个别耦元去除法，利用磨料磨损试验机分别考察了形态、结构、材料等耦元对毛蚶及脉红螺壳体磨料磨损性能的影响。通过对磨损试验结果进行对比分析，揭示了各耦元对毛蚶壳体耐磨性能的贡献度，即有机质材料为主耦元，棱纹形态为次主耦元，棱纹与小结节组成的复合结构为一般耦元；并分别对其耐磨机理进行了分析。论文同时对毛蚶与脉红螺壳体磨料磨损的各向异性机理进行了研究。磨料磨损试验结果表明，毛蚶壳体具有最优的耐磨料磨损特性；而冲蚀磨损试验结果也表明，石鳖体表具有良好的抗冲蚀磨损特性。本文同时对这三种贝类壳体结构与功能的适应性进行了探索性分析。根据毛蚶壳体耐磨料磨损生物耦合特性，分别建立了形态单元仿生模型、形态-结构与形态-材料二元耦合仿生模型，并利用ANSYS/CFX专业流体计算软件分别对这几种模型的磨料磨损流场进行了数值模拟。通过对比分析磨损过程中各模型流体域与固体域的力学性能参数，对不同模型的耐磨性能进行评估。结果表明，形态-结构二元耦合仿生模型相对于形态单元仿生模型，始终表现出最优的耐切削与抗冲击性能，即棱纹与小结节组成的复合结构可以有效降低流体速度，减小流体作用力，削弱磨料粒子对壁面的剪应力，使固体域接触应力显著降低，从而使模型表现出良好的耐磨料磨损性能。形态-材料二元耦合仿生模型由于表面发生塑性形变而使单向流固耦合模拟结果可靠性降低，论文进一步对其磨损机理及模型优化进行了探讨分析。利用ANSYS/LS-DYNA显式动力分析软件，对仿石鳖壳板的构形单元仿生模型和构形-凹槽形态及构形-凸包形态二元耦合仿生模型的动态冲蚀磨损过程进行了三维数值模拟，对比分析了不同耦元对靶材抗冲蚀性的影响规律。三种模型在整体水平上抗冲蚀性顺序依次为凸包弧形板、凹槽弧形板和光滑弧形板。在弧形板峰部，凹槽的应力分散效应即抗冲蚀性能明显优于凸包；而在翼区，凸包的抗冲蚀性能显著优于凹槽，说明石鳖壳板在进化过程中优化出了最佳的形态组合，即壳板峰部分布有粗大的纵肋（肋间相对形成凹槽），而翼区则分布有大量的凸包，从而可以有效抵抗强烈的海砂冲蚀。通过对三种典型贝类壳体的生物耦合耐磨特性进行研究，进一步证明耦合仿生比单元仿生更接近于生物真实的作用机理，将产生更好的仿生效能。因此，对耦合仿生进行深入研究将加快仿生从形似到神似的进程，具有重要的理论价值与实践意义。更多还原

【Abstract】 Abrasion could be described as a process of wearing down or rubbing away by means offriction between the contact bodies during relative motion. Abrasion exists extensively inengineering field, and causes serious material and equipment failure. According to thestatistics, the failure of80%of mechanical parts or more is due to wear and tear, and30-50%of global energy consumption is attributed to friction and abrasion. Abrasion not onlyconsumes material, but also wastes energy, and directly affects the life and reliability ofmechanical parts. Thus, the abrasion becomes a problem to be urgently conquered nowadays,and perhaps such solutions could be learned from the nature. Biological creatures live inharmony with nature upon the combination of multiple factors, e.g. surface morphologies,complex structures and component materials, and achieve the optimum adaptation to thesurroundings based on such biological coupling functions. So in the current study, threetypical molluscan shells Scapharca subcrenata, Rapana venosa and Acanthochitonrubrolineatus were selected to study their biological coupling and bionic anti-wear properties.The paper tries to provide reference information for the development of innovated anti-wearcomponents as well as for the complement of the coupling bionic theory.Molluscan shells are fascinating examples of highly ordered hierarchical structure andcomplex organic-inorganic biocomposite material. The selected shells S. subcrenata, R.venosa, and A. rubrolineatus are typical molluscan species respectively belonging toimmersed, demersal crawling and attached crawling life forms, and involving the threerepresentative species of mollusca including Bivalvia, Gastropoda and Polyplacophora. Theseshells have specific living behaviors and exhibit exceptional wear resistant properties. In thispaper, more experimental methods were applied to study their biological, mechanical andwearing properties. And the large finite element analysis software ANSYS was further usedto simulate the abrasive and erosive process of the built uni-bionic models and thedual-bionic coupled models. The biological coupling and bionic anti-wear properties of thesethree typical molluscan shells thus were preliminarily revealed in this paper. During the biological coupling analysis, the stereomicroscope, SEM and X-ray diffractionwere respectively used to investigate the surface morphologies, microstructures and phasecompositions of the shells. Observations showed that the surface morphology of the left shellof S. subcrenata is much complicated distributed with radial riblets coupled with nodules.The crossed lamellar structure was found generally existing in the three shells displayedhighly ordered hierarchical structure. In S. subcrenata and A. rubrolineatus, the specificwell-developed pore canal tubules were also discovered. According to the phase components,aragonite is the most extensive phase present in the molluscan shells, which could effectivelyresist the external damage. Micro-Vikers hardness test demonstrated that the micro-hardnessof each layer closely relates to its corresponding microstructures and shows anisotropy. Thecrossed lamellar structure in the sub-layer of S. subcrenata and the nacre layer of R. venosashowed the highest micro-hardness, and the similar structure in the chiton also displayedrelatively high micro-hardness. Compressive test indicated that the bearing capacity of thelayered section of the shells is higher than that of the transverse section. The compressivestrength of the shell also corresponds to its microstructures.In the abrasion test, the methods of separate testing and selective removing of the individualcoupling element were used to respectively investigate the effects of coupling elements e.g.morphology, structure and material on the abrasive properties of the shells of S. subcrenataand R. venosa by the rotary-disk type abrasive wear tester. Through comparative analysis, theimportance degree of different coupling elements during the abrasive process of the shell of S.subcrenata was revealed, that is the organic material could be classified as the main couplingelement, riblet morphology could be considered as the hypo-main coupling element, and thecomplicated structure composed with riblets and nodules could be regarded as the normalcoupling element. The wear-resistant mechanisms of each coupling element were alsoanalyzed. At the same time, the abrasion anisotropies of the shells of S. subcrenata and R.venosa were studied and analyzed. The experimental results demonstrated that the wearresistant property of the shell of S. subcrenata is the best, while that of the R. venosa isrelatively not prominent. The tentative erosion test preliminarily indicated that the bodysurface of the chiton exhibits strong erosion-resisting merits. The relationship between thestructure and the function of the three shells were also explored in this paper. According to the biological coupling anti-wear property of the shell of S. subcrenata, thesurface morphology uni-bionic model, the morphology-structure and themorphology-material dual-bionic coupled models were independently constructed, and thecomputational fluid dynamic software ANSYS/CFX was applied to simulate the abrasiveprocess of the models. The simulation results showed that the anti-cutting and anti-erosionproperty of the morphology-structure coupled model was generally better than that of themorphology uni-bionic model. It means that the complicated structure composed with ribletsand nodules could effectively decrease the velocity and the forces of the fluid, weaken thewall shear stress of the model, and in final reduce the contact stresses of the solid domain.The morphology-material coupled model probably underwent deformation during theabrasion process and caused the incorrect result of one-way coupling simulation. Theabrasion mechanism and the model optimization were further proposed in the paper.The explicit dynamic software ANSYS/LS-DYNA was used to simulate the erosive processof the configuration uni-bionic model and configuration-groove/convex morphologydual-bionic coupled model imitating the shell surface of chition. The mechanism of erosionof each model was comparatively analyzed. The overall erosion resistance of the threemodels was sorted as convex-curved plate, groove-curved plate and smooth-curved plate.However, in the peak of the curved plate, the stress dispersion effect of groove is much betterthan that of convex, whereas the stress dispersion effect of convex is better than that ofgroove at the pterion region. The simulation results indicated that the shell plate of chitonevolved an optimum combination of morphologies with thick riblets distributed in the peak(grooves are thus formed between the riblets) and convexes scattered around the pterionregion, and thus endow the chition with exceptional wear resistance.The study on biological coupling anti-wear properties of typical molluscan shells furtherproved that coupling bionics is more nearly to the real function mechanism of the biologicalcreatures and thus produce better efficiency. Therefore, the further study on coupling bionicswould greatly promote the process from similar in appearance to similar in spirit andundoubtedly would be of great theoretical value and practical significance.更多还原