超低温环境下树脂基复合材料力学性能评价与失效机理

Lightweight composite structure has been widely used in the aerospace field as load-bearing component, and the performance of composite structures is significantly influenced by extreme environments, such as cryogenic temperature, high-low temperature cycling, and mechanical-thermal coupling. In fact, due to the lack of in-situ characterizations of mechanical performance evolution and micro-failure mechanism under extreme conditions, the safety and reliability design of composite structures face serious constraints. In present work, the fiber reinforced resin composite used under cryogenic temperature will be studied. An in-situ characterization method will be developed to reveal the mechanical performance evolution, micro-structure damage propagation, and their mapping relation. Based on the experimental results, the nonlinear gradual failure model and strength criterion will be proposed, taking into account the effects of environment temperature and alternation cycles. The image-based finite element modeling method and simulation approach will be developed, to predict the mechanical performance of composite structure containing real microscopic defects under the complex loading conditions. We expect to gain original achievements in characterization method, failure mechanism and simulation approaches, which can provide the technique and theoretical guidance for the composite structure application in the equipment served under cryogenic temperature environment.

航空航天装备轻量化复合材料结构，面临的超低温环境、高低温交变和力-热耦合效应影响极其显著，由于缺乏超低温环境下复合材料力学性能演化规律与微细观失效机理原位表征研究，低温环境服役轻量化结构的安全性和可靠性设计受到了严重制约。本项目以应用于超低温环境下的纤维增强树脂基复合材料为研究对象，旨在通过发展超低温环境下材料的微细观失效机理原位测试手段与表征方法，揭示环境因素耦合效应下复合材料宏观力学性能演化规律，以及内部微细观结构损伤演化形式与宏观力学特性的映射规律；基于实验表征结果，建立兼顾环境温度和交变循环周期影响的复合材料非线性渐进失效分析模型与强度失效判据；发展含真实微观缺陷复合材料的图像有限元建模方法，给出复杂载荷环境下材料力学性能数值计算方法。期望在实验表征方法、失效机理和数值计算分析方法等方面获得原创性成果，为复合材料在超低温环境服役装备上的应用提供理论和技术支撑。

超低温环境是航天器装备复合材料构件服役安全性设计和可靠性评价面临的新挑战，核心难题是揭示低温环境对复合材料性能影响的内在力学机制，建立准确的超低温环境下复合材料力学性能预示模型。本项目围绕超低温环境下树脂基复合材料力学性能评价方法与失效机理开展研究，创新搭建了超低温环境μ-CT原位加载测试表征系统，以及力-热耦合环境渗漏测试表征系统，探明了超低温环境对复合材料强度、模量和宏微观失效模式的影响机理，建立了考虑温度影响效应的复合材料静动态强度理论与失效判据，明晰了环境温度、应力状态对复合材料层板微裂纹渗漏的影响机制，发展了基于μ-CT扫描裂纹数据统计模型的复合材料层板渗漏率计算新方法，实现了不同温度、不同应力状态下复合材料渗漏率的高效率计算，提出了基于U-net深度学习网络的二维图像处理新方法，以及三维数字模型体素网格建模方法，解决了低对比度图像的高效率识别难题。累计发表SCI学术论文18篇，申请国家发明专利4项，参加国内外学术会议7次，培养博士后1名、研究生6名。研究成果为航天一院牵头研制的我国首个复合材料贮箱原理样机提供了理论和技术支撑。