自愈合CMC-SiC复合材料的热力氧耦合损伤本构及强度理论研究

自愈合碳化硅基体复合材料（CMC-SiC）的服役工况涉及热力氧耦合。热力氧联合作用下，CMC-SiC材料的各向异性损伤本构及强度理论研究不够，严重制约了其在航空航天耐热承力结构中的应用。本项目拟开展CMC-SiC材料在高温有氧复杂应力下的多尺度损伤机理与承载性能研究。针对典型自愈合CMC-SiC材料，开展热力氧耦合加载下的强韧性试验，研究多尺度损伤演化机理、破坏模式与承载性能，阐明热力氧损伤的耦合机制及微裂纹的失稳机制。提出模拟环境下材料的氧化动力学模型、各向异性本构模型和强度失效模型。应用新理论，开展复杂气氛-应力下CMC-SiC材料的渐进损伤模拟，提出承载性能的预测模型和方法，阐明宏观性能演变与细观物理-化学损伤的关联机理。通过本项目的研究，有望进一步发展陶瓷基复合材料本构、强度的表征理论和方法，提升CMC-SiC热结构的强度设计水平，促进材料承载潜力的发挥，取得一定的社会与军事效益。

The application conditions for self-healing silicon carbide matrix composites (CMC-SiC) involve thermo-mechanical-oxygenic coupling. However, the anisotropic damage constitutive relationship and strength theory of CMC-SiC composites under heat-force-oxygen combined loadings are not studied comprehensively. This has seriously restricted the design and application of heat-resisting structures with CMC-SiC material in aerospace field. In this project, the multiscale damage mechanisms and bearing capacity of CMC-SiC composite structures under extreme conditions of high temperature, oxidative atmosphere and complex stress would be investigated. The strength and toughness experiments under thermo-mechanical-oxygenic coupled loadings will be conducted on typical CMC-SiC composite materials. The multiscale damage evolutions, failure modes and bearing capacity of specimens will be studied. Meanwhile, the interaction mechanism of the thermal, mechanical and oxygenic damages and the instibility mechanism of microcrack extension will be demonstrated. The oxidative dynamics model, anisotropic constitutive model and strength failure model under simulated environment would be established. By the newly proposed theory, progressive damage simulation upon CMC-SiC composites and structures under complex atmosphere-stress will be performed. Predictive methodology and model for load-carrying property will be developed. Furthermore, correlation mechanisms of the macroscopic properties with physical-chemical damage will be illuminated. Through the studies in this project, representation theory and methodology for constitutive relation and strength of ceramic matrix composites are expected to be developed in order to promote the strength design of CMC-SiC hot structures, to facilitate the use of load-bearing potential of materials, and to make social and military benefits obviously.