基于三维机织碳／碳复合材料的细观结构特征，设计平板十字形试样，在材料双轴力学性能试验机上开展了复合材料单轴、双轴加载压缩试验，对比分析了三维机织碳／碳复合材料在双轴压缩载荷下的力学行为。研究表明：三维机织碳／碳复合材料的压缩行为表现为非线性、脆性断裂；双轴载荷作用下非线性特征更为显著，压缩模量随应力的增加而增大，强度与模量相较于单轴有较大幅度增加，双轴压缩载荷作用下材料的强化效应显著；试样破坏位置并未出现在试样中心区，而是发生在试样的加载端部或十字形试样的加载分枝根部，主要表现为基体开裂、纤维断裂和层间脱粘，碳布及其层间界面剪切强度的强弱直接影响材料的压缩强度。%Based on the mesoscopic structure of the three-dimensional woven carbon/carbon (3D C/C) composite materials, a kind of flat cross- shaped specimen was designed followed by the test on biaxial mechanical testing machine under uniaxial and biaxial compression as well. Comparative analysis was carried out for the mechanical behavior of the 3D C/C composite materials under biaxial compression loading. The results show that the 3D C/C composite materials represent the non-linear compression behavior and brittle fracture. The nonlinear characteristics under biaxial loading are more significant, and the compression modulus increases along with the increase of stress. The strength and modulus of 3D C/C composites increase sharply under biaxial loading compared with the uniaxial results, and the enhanced effect of the material is remarkable. In addition, the fracture doesn't appear in the central area of the specimen, but in the loading ends or the branch of the cross-shaped specimen. The main damages are matrix cracking, fiber breakage and interlaminar debonding. The compressive strength is affected directly by the carbon fiber cloth and the interlaminar shear strength of the material.
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