基于云理论的热解炭基C/C复合材料微观结构-力学性能量化关系研究

According to the problem of the uncertainty on the characterization of C/C composites' microstructure, the dispersivity on the data of mechanical properties and the non-quantity of the analysis of the relationship between microstructure and mechanical properties, the cloud theory will be introduced into the analysis of materials' microstructure and properties in this project. A thorough research that focuses on the quantitative characterization of microstructure and credible prediction of mechanical properties will be implemented through the uncertain conversion between qualitative concept and quantitative concept. The principal factors of microstructure features that affect the mechanical properties will be determined by studying of image segment and feature information extraction methods based on cloud model, quantitative evaluation technology of random microstructure, 3D reconstruction technology and numerical simulation method of mechanical properties. On the basis, a lot of technological problems that include design of the cloud inferers, determination of the membership clouds' vector spaces, generalization of the fuzzy inference rules and construction of the forward and backward cloud models will be studied by combining the mechanical properties' test data, and then the quantitative analysis model of the relationship between microstructure and mechanical properties will be built, which provides a theory basis for improving the development of CVI preparation technology and designing of the microstructure of C/C composites. It means that the quantitative characterization of microstructure and valid prediction of mechanical properties will be achieved to the C/C composites.

本项目针对C/C复合材料微观结构表征的不确定性、力学性能数据的分散性以及难以建立其量化关系的国际性难题，提出将云理论的基本思想引入到C/C复合材料微观结构表征和力学性能预测中，借助云理论对定性概念和定量变量间的不确定性转换功能解决微观结构识别和力学性能表征中存在的不确定性问题。通过系统研究基于云模型的图像分割、特征信息提取、随机微观结构量化技术，PLM图像三维重构技术和力学性能数值模拟技术，确定影响C/C复合材料力学性能的主要微观结构因素；在此基础上，结合力学性能试验测试数据研究微观结构与力学性能间的云推理器的设计、隶属云向量空间的确定，模糊推理规则提取，正向和逆向云模型的构建等科学技术问题，建立微观结构-力学性能量化分析模型和云预测系统，从而实现对热解炭基C/C复合材料微观结构的量化表征及力学性能的有效预测。为推动CVI工艺的深化研究和发展以及C/C复合材料的细观设计奠定理论基础。

针对C/C复合材料微观结构特征难以定量表征、微观结构和力学性能参数之间联系难以描述的国际性难题，提出将云理论的基本思想引入到 C/C 复合材料微观结构表征和力学性能预测中，系统研究基于云模型C/C复合材料的图像分割、特征信息提取、微观结构信息定量表征技术。实现基于C/C复合材料PLM图像的微观组分识别和表征；在此基础上，结合C/C复合材料力学性能实验测试数据，确定影响复合材料力学性能的主要微观结构因素。采用基于等效夹杂张量的平均场均质法和基于代表性体积单元的数值均质法，预测C/C复合材料的等效热-弹性性能，探究不同微观结构参数对C/C复合材料等效刚度影响规律。通过用于自定义单元法创建无厚度黏聚区单元对C/C复合材料的开层断裂进行描述，通过子程序USDFLD和UMAT定义C/C复合材料损伤刚度退化规则和断裂规则，预测C/C复合材料的断裂强度和失效形式。从而实现对热解炭基 C/C复合材料微观结构的量化表征及力学性能的有效预测。为推动C/C复合材料性能预测以及 C/C 复合材料的细观设计奠定理论基础。