具有多级微结构的生物材料磨损特性跨尺度建模、数值模拟和试验验证

Biomaterials usually exhibit excellent mechanical properties, such as high stiffness, high toughness, high resistance to wear or fatigue, with which few artificial materials are endowed. To a large extent, this comes from the optimized hierarchical microstructures of biomaterials formed after a long biological remodeling process. Most of the biomaterials hierarchically structured consist of mineral inclusions embedded in an inorganic matrix, with different material properties and organization at different scales. The study of the friction and wear of biomaterials is currently limited to considering only a given scale, so that it is difficult to be able to reveal their characteristics and mechanisms. The research work proposed in our proposal is concerned with the multi-scale modeling and simulation of the wear behavior of human enamel,a representative object, as a prototype of biomaterials. First, through performing experimental wear tests and carrying out structural organization and material composition analysis at different scales, the work aims to establish the method of quantifying the wear characteristics of human enamel at each level. Further, with the help of micromechanics theory and numerical simulations, the wear parameters at a given scale will be expressed in terms of the material properties and the microstructure at a smaller scale. At the same time, the comparison of the experimental results with the results obtained by the theoretical modeling and numerical simulation is expected to clarify the wear mechanisms of human enamel. Finally, a numerical platform dedicated to simulating the wear behavior of biomaterials will be constructed. The results of the research work presented in this proposal are expected not only to contribute to enriching the framework of wear theory for multi-scale hierarchical biocomposites, but also to be useful for the choice and design of wear-resistant engineering materials.

生物材料通常具有人工材料难以比拟的强度、柔韧、抗磨损、抗疲劳等特性。在很大程度上这来自于生物体通过长期进化而形成的优异多级微结构。生物材料微结构多为有机相包裹矿物质通过有序组装而形成，在不同尺度上具有不同的材料特性和组织方式。当前生物材料摩擦磨损研究局限于单尺度，难以揭示其基本特性和机理。本课题采用代表性对象牙釉质开展生物材料磨损特性与机理的跨尺度表征、建模和模拟。首先，通过牙釉质不同尺度的磨损试验及其结构组织方式和材料成分分析，建立不同尺度微结构的磨损特性和定量表征方法。进而，借助细观力学理论和数值模拟方法，获得不同尺度间牙釉质的磨损参量与结构组成、材料参数的关系，同时通过数值模拟规律与试验特征对比揭示其磨损机理。最终，开发集成不同尺度微观特性的生物材料磨损过程模拟平台。本课题的成果不仅具有进一步丰富生物材料磨损机理的理论意义，且对耐磨工程材料选取和设计有所帮助。

生物材料止裂耐磨的优异特性与多级微结构密切相关。生物材料微结构多为有机相包裹矿物质通过有序组装而形成，在不同尺度上具有不同的材料特性和组织方式。当前生物材料摩擦磨损研究局限于单尺度，难以揭示其基本特性和机理。本课题采用代表性对象牙釉质开展生物材料磨损特性与机理的跨尺度表征、建模和模拟。主要进展包括：.（1）非均质材料磨损行为的多尺度理论建模：采用细观力学方法对牙釉质复合材料的磨损特性进行跨尺度建模，目的是建立复合材料宏观磨损系数与微观几何特征和材料特性的定量描述，阐明复合材料各组分的弹性、粘弹性及弹塑性、微观结构对宏观磨损性能的影响。.（2）基于牙釉质特征的纤维复合材料宏观磨损预测的数值方法：建立描述类牙釉质的纤维复合材料磨损过程的有限元模型，通过接触分析和磨损计算，定量分析滑动过程中纤维复合材料的宏观和各组分的磨损系数的变化规律、磨损形貌的渐变特征演化规律，建立宏观磨损率与两相材料特性、形状参数、局部摩擦力的定量关系，揭示磨损各向异性的纤维取向结构调控机制。.（3）牙釉质多级微观结构的自动建模和有效模量预测：基于水平集方法，建立牙釉质多级微结构自动建模方法，实现复杂非均质材料的准确重构。.（4）基于相场法的脆性断裂疲劳裂纹扩展数值计算方法：基于相场法相关理论，建立裂纹拓扑模型与断裂相场的微分方程，通过有限元离散，并结合疲劳裂纹扩展理论，对应力强度因子、应变能和疲劳裂纹扩展速率等的计算方程进行有限元离散，开发基于MATLAB语言的有限元程序。.本项目相关研究成果已发表SCI检索论文7篇，会议论文1篇，发明专利1项，软件著作权3项。培养博士生2人，硕士生6人。

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