三维角联锁CF/Al复合材料准静态变形细观损伤演化与失效行为及其对宏观性能影响机理研究

3D angle-interlock CF/Al composites have high specific strength and modulus, good ageing resistance and thermal stability as well as excellent structural integrity and designability, which can be applied potentially in the aerospace fields. However, there is a noticeable lack of systematic study on the microscopic damage and failure mechanism of this composite, due to the multiscale influence of meso-structure and interface behavior on the macro-properties. In this project, multi-scale analysis and experimental research on microscopic and macroscopic mechanical behavior of the composites during quasi-static deformation was proposed based on a hierarchicalin numerical model. The unit cell FE model of the unidirectional composites will be established using the mechanical testing on matrix, fiber and interface bonding. The ductile matrix fracture and brittle fiber fracture, especially the progressive damage and debonding of interface will be investigated and their influence mechanism on the macroscopic fracture behavior of the unidirectional composites will be revealed. The orthotropic constitutive behavior of the unidirectional composites will be calculated using homogenization method. Based on the elastoplastic mechanical properties and interface damage criterion of the unidirectional composites, the meso-mechanics FE model was established to analyze the dynamic stress response of matrix alloy and unidirectional composite bundle, and the damage and fracture behavior of the interface during the quasi-static tensile deformation. Based on the mean field method, the macroscopic mechanical responses will be calculated and compared with the mechanical testing ones. According to the results from micromechanics analysis as well as macro-fracture analysis, the dominant fracture mechanism of the 3D-CF/Al composites will be discussed both in microscopic and macroscopic level. By the micromechanics FE analysis, the fracture mechanism of the composites with different meso-structure parameter will be discussed, and the effect of meso-structure parameters on macroscopic mechanical behaviors will be investigated. Combining the results of micromechanics FE analysis and mechanical testing, the dependence of macroscopic mechanical behaviors on meso-structure parameter will be investigated. The results can provide a sound foundation for understanding the underlying fracture mechanism of the composites and guidance for manufacturing high-performance 3D-CF/Al composites component through collaborative design between the meso-structure/macro-properties.

三维CF/Al复材继承了单向CF/Al复材高强高模及耐热性好等优点，且具有结构整体性和各向性能可设计性，是航空航天领域极具应用潜力的新型金属基复合材料。因复杂细观结构与界面行为对宏观性能影响的多尺度性，目前缺乏其宏细观损伤与失效机理的研究。本项目开展其准静态变形宏细观断裂失效行为的分层次多尺度模拟与实验研究，通过组元材料和界面就位性能试验，建立单向CF/Al复材微观层次单胞FE模型，分析基体与纤维损伤断裂及界面渐进损伤与脱粘行为，揭示其对宏观断裂力学行为作用机制；均匀化计算单向复材正交异性宏观力学性能并利用其界面损伤失效准则，建立三维CF/Al复材细观层次单胞FE模型，研究基体/复材束及其界面损伤演化与破坏行为，结合实验揭示其断裂失效机理；分析三维复材结构参数对组元及界面损伤失效行为影响规律，揭示宏观力学性能对细观结构依赖关系，为高性能三维CF/Al复材制备及宏细观结构与性能控制奠定基础。

三维编织结构纤维增强铝基复合材料具有轻质、高强高模、高耐热及良好结构完整性和性能可设计性，在高推重比发动机和高马赫数武器热部件上极具应用潜力。针对其承载变形宏细观力学特性与失效机理问题，本项目采用多尺度数值模拟和实验结合的方法开展其面内载荷下的渐进损伤与断裂力学行为研究。完成了单向铝基复合材料组分材料与界面性能实验研究，建立了基体合金、纤维和界面的材料力学性能模型；根据三维编织铝基复材组织结构特征，构建了纤维/基体/界面的微观尺度单胞和纱线/基体/界面的细观尺度单胞模型，解决了基体合金延性损伤、界面损伤脱粘以及纱线（纤维）各向异性断裂力学行为表征等关键技术，建立了三维编织铝基复合材料的多尺度非线性力学分析模型；三维编织铝基复材经/纬向拉伸宏观应力-应变曲线的均匀化计算结果与实验结果吻合良好，拉伸强度、模量和延伸率计算误差均小于10%，经/纬向拉伸载荷下复材首先发生界面和基体的局部损伤，二者的损伤和累积依次引发经纬纱线交织处界面和基体合金局部失效、以及内部纱线的横向开裂现象，数值模拟和断口实验结果表明，作为主要承载组元纱线的轴向断裂是导致复材发生宏观失效的主要机制；三维编织结构复合材料经/纬向拉伸性能影响的数值模拟和实验结果表明，其纬向拉伸强度、模量和延伸率分别是经向的81.8%、56.5%和74.7%，减小经纱层间距可显著提高复材的经/纬向拉伸强度、模量和延伸率，复材的经向拉伸强度和模量随纬纱层间距的增大而增加，纬向拉伸强度和模量则随纬纱层间距增大而减小。研究成果不但为三维编织结构铝基复合材料高性能设计制备提供了理论依据，而且为其工程结构的设计、开发和应用奠定了坚实基础。