中文摘要：

基于连续损伤理论，推导了含损伤裂纹的正交各向异性材料的应力一应变关系。建立了考虑界面脱粘破坏的三维五向编织复合材料细观体胞模型，并将有限元网格尺寸和单元裂纹尺寸引入损伤演化方程。采用Hashin准则和von—Mises准则分别判断纱线与基体的初始损伤，结合Eshelby—Mori—Tanaka方法确定材料的刚度退化系数。利用ANSYS有限元软件对材料进行渐进损伤分析，得到了材料在单向拉伸作用下的应力一应变曲线和极限强度。计算结果表明，轴纱为材料的主要承力部分，小编织角材料的破坏模式主要为纱线的拉伸断裂，界面破坏情况较为严重。模拟计算结果与实验结果吻合较好。

英文摘要：

Based on the continuum damage theory, the stress - strain relationship for orthotropic materials with damage cracks was derived. A representative volume unit cell for 3D five- directional braided composites was constructed, in which the debonding on the interface was considered. The sizes of the finite element mesh and the crack were considered in the damage evolution equation. The Hashin and von-Mises criteria were used for prediction of the initial damage of yarns and matrix, and the Eshelby- Mori- Tanaka method was applied to calculate the stiffness reduction factor. The progressive damage behaviors were simulated by ANSYS, and the stress - strain curve and the critical strength under uniaxial tensile loading were obtained. It is shown that the main failure mode of the composites with a low braiding angle is yarn cracking with serious damage on the interface. The results from the simulation agree well with the experiments in the existing literature.