非一致随机分布编织C/SiC复合材料多尺度损伤模型研究

Woven C/SiC composites are one class of key cornerstone materials for the future development of aeronautical and aerospace technology, owing to their excellent performances such as high temperature resistance, low density, high strength and high fracture toughness. The temporal and spatial distribution characteristics and interactions of microscopic toughening mechanisms for C/SiC composites and the interactions between key damage mechanisms have strong effects on macroscopic fracture behavior for composite materials. The homogenization method for fiber cluster with multiple cracks is proposed by perturbation theory and CDM theory. By the determination of the damage property in cluster elements with non-uniformly random distribution method, the multi-scale, fiber-fiber cluster-fiber bundle-woven structure, damage accumulation process of woven C/SiC composite material is simulated by progressive damage analysis method using the cohesion-type degradation criteria. The correlation model between the statistical parameters of component materials and macroscopic mechanical variables is established. Considering the fiber cluster as a medium with a crack, the competing propagation and joint interaction mechanisms of these cracks for C/SiC woven composites are revealed by using the extended-FEM method. The expected research results can also be widely applicable to the damage analysis for most other inhomogeneous materials, such as CMC materials with different reinforcing woven structures and different components.

编织C/SiC复合材料具有耐高温、低密度、高强度和高韧性等一系列优异性能,是未来航空航天科技发展的关键支撑材料之一。该材料的各种细观增韧机制的时空分布特征及相互作用会强烈地影响材料的宏观断裂行为。本项目拟采用摄动均匀化理论和连续损伤力学方法提出含多裂纹纤维簇的均质化方法；基于非一致随机分布方法确定每个纤维簇单元中的损伤性能；基于内聚力型退化准则，采用渐进损伤分析方法模拟编织C/SiC复合材料进行单纤维-纤维簇-纤维束-编织结构多尺度的损伤累积过程，建立组分材料统计参数与宏观力学变量之间的关联模型。把纤维簇等效为含单裂纹材料，采用扩展有限元方法揭示编织C/SiC复合材料群裂纹的多尺度竞争扩展和串接机制。本项目给出了C/SiC材料失效问题多尺度分析的新思路，研究成果可用于分析不同编织CMC材料的裂纹扩展及失效研究，还可为其它非均质材料的损伤演化分析提供借鉴，具有重要的学术意义和应用价值。

在有限元模型中采用非一致随机分布方法引入组分材料的统计分布因素，更好的揭示了复合材料的细观破坏机制，研究了组份材料对宏观性能的影响，获得了满足最优材料韧度、强度和弹性性能等不同设计要求的最优细观结构和组分材料统计性能的最优匹配。提出了C/SiC纤维束的裂纹扩展模拟方法，基于细观力学理论建立多尺度有限元分析模型,模拟了单纤维-纤维簇-纤维束-编织体损伤的累积过程，采用损伤张量对含多裂纹纤维束进行各向异性性能等效，借鉴内聚力思想提出了渐进损伤分析中新的各向异性材料退化准则，应用新的含多裂纹非均匀介质的多尺度渐进分析方法，建立了新的多尺度损伤数值本构模型。结合纤维束和编织材料的试验研究揭示了编织 C/SiC 复合材料变形和断裂机制，为复合材料细观结构的强韧化优化设计提供重要的理论依据。