In this paper, the effect of pre-fatigue loading on tensile damage and fracture of fiber-reinforced ceramic-matrix composites (CMCs) is investigated using a micromechanical approach. Under cyclic fatigue loading, the fiber/matrix interface shear stress degrades with applied cycles due to the damage mechanism of the interface wear. The micro stress field of the damaged composite including matrix cracking, fiber/matrix interface debonding, and fiber failure is obtained for the fiber and the matrix axial stress and the fiber/matrix interface shear stress in the interface wear region, interface debonding region, and the interface bonding region, respectively. The fracture mechanics approach, stochastic matrix cracking model, and global load sharing (GLS) criterion are used to determine the interface debonding length, matrix cracking density, and fiber failure probability at higher applied stress level considering the damage mechanism of the interface wear. The effects of fiber volume, matrix cracking, fiber/matrix interface shear stress, fiber strength, pre-fatigue peak stress, and number of cycles on pre-fatigue tensile damage and fracture of SiC/SiC composites are analyzed. The experimental tensile damage and fracture of SiC/SiC composites with and without pre-fatigue loading are predicted for different interface properties.

本文采用微机械方法研究了疲劳前载荷对纤维增强陶瓷基复合材料（CMCs）的拉伸损伤和断裂的影响。在循环疲劳载荷下，由于界面磨损的破坏机理，纤维/基体界面剪切应力随着施加的循环而降低。获得了受损复合材料的微应力场，包括基体开裂，纤维/基体界面剥离和纤维破坏，以及在界面磨损区，界面剥离区和基体中的基体轴向应力和纤维/基体界面剪切应力。界面结合区。断裂力学方法，随机矩阵裂纹模型和整体载荷分担（GLS）准则用于确定界面剥离长度，矩阵裂纹密度，考虑到界面磨损的破坏机理，在较高的施加应力水平下纤维和纤维的破坏概率。分析了纤维体积，基体开裂，纤维/基体界面剪切应力，纤维强度，疲劳前峰值应力和循环次数对SiC / SiC复合材料疲劳前拉伸损伤和断裂的影响。预测了具有和不具有预疲劳载荷的SiC / SiC复合材料的实验拉伸损伤和断裂对于不同的界面性能。