缺陷对编织复合材料热应力影响的图像有限元方法与机理研究

Manufacturing defects in textile composites not only affect the transmission of heat and force, but also significantly change the diffusion path of oxygen, which in turn changes the distribution and magnitude of thermal stress inside the materials. At present, it is still hard to simulate the thermal stress of braided composites accurately, and the mechanism of defects on thermal stress is not clear. This project studies the image-based Finite Element Method of braided composites; develops high fidelity identification and efficient processing method for braided composite CT images; establishes the contour-based intelligent multi-layer nested grid generation method, particularly, studies the mapping relationship between the component material properties and the grayscale of the digital images. For the thermo-mechanical- oxidation coupling response of braided composites, combined the sticky-elastic-plastic large deformation constitutive relationship and the high temperature oxidation kinetic model to establish the thermo-mechanical-oxidation coupling large deformation nonlinear constitutive model of the materials. Through the image-based FEM approach, investigate the influence of typical manufacturing defects on the distributions, magnitudes and evolution behaviors of thermal stress of braided composites under extreme service loadings; reveal the mechanism of those effects.

编织复合材料的制造缺陷不仅影响力、热荷载的传递路径，同时显著改变氧元素的扩散路径，改变材料内部热应力的分布与量值。目前针对编织复合材料的热应力精确模拟还存在困难，缺陷对热应力的影响机理尚不明确。本项目从编织复合材料的图像有限元方法研究入手，发展编织复合材料CT数字图像高保真识别与高效处理方法，建立基于轮廓的智能多层嵌套网格生成方法，深入研究组元材料性能参数与数字图像灰度的映射关系；针对编织复合材料的热-力-氧耦合力学响应，将大变形粘-弹-塑性本构模型与高温氧化动力学模型相结合，建立材料的热-力-氧耦合大变形非线性本构关系；基于编织复合材料的图像有限元方法，研究极端服役荷载下典型制造缺陷对编织复合材料热应力分布、量值与演化行为的影响规律，揭示缺陷影响的力学机制。

按照项目任务书的研究内容和研究进度安排，本项目从C/SiC编织复合材料的图像有限元建模方法研究入手，发展了C/SiC编织复合材料CT数字图像高保真识别与高效处理方法，建立基于轮廓数据的有限元网格生成方法，系统开展了C/SiC复合材料组元材料的力学性能实验测试；针对C/SiC编织复合材料在典型服役工况下的热-力-氧耦合力学响应，本项目将大变形弹-塑性本构模型与高温氧化相场模型相结合，建立了C/SiC材料的热-力-氧耦合大变形非线性本构关系；基于本项目建立的编织复合材料的图像有限元方法，研究极端服役荷载下典型制造缺陷对C/SiC编织复合材料热应力分布、量值与演化行为的影响规律，揭示了缺陷影响的力学机制，完成了项目预定的研究内容，取得了较丰富的研究成果。