In this paper, stress rupture of fiber-reinforced ceramic-matrix composites (CMCs) subjected to different stochastic loading spectrums at intermediate temperatures (600 to 1000 °C) is investigated. Under stress rupture at stress level higher than the first matrix cracking stress, multiple damage mechanisms of matrix cracking, fiber/matrix interface debonding, interphase and fiber oxidation, and fiber fracture are considered to analyze evolution of composite strain. Four different stochastic loading spectrums are considered in the analysis of damage evolution and lifetime of fiber-reinforced CMCs under stress rupture loading. Relationships between stochastic loading stress, frequency, time, interface debonding and oxidation length, fiber failure probability, and stress rupture lifetime are established. Effects of stochastic loading stress and time, fiber volume, matrix crack spacing, interface debonding energy, interface shear stress, and temperature on composite strain, interface debonding and oxidation length, and the fiber failure probability versus time are analyzed. Experimental stress rupture strain and lifetime of SiC/SiC composite under constant stress and stochastic loading spectrums are predicted. When the stochastic loading stress, frequency, and temperature increase, the stress rupture lifetime and the time for the interface complete debonding and oxidation all decrease.

本文研究了纤维增强陶瓷基复合材料（CMC）在中间温度（600至1000°C）下承受不同随机载荷谱的应力破裂。在高于第一个基体开裂应力的应力水平下的应力断裂下，考虑了基体开裂，纤维/基体界面剥离，相间和纤维氧化以及纤维断裂的多种破坏机理，以分析复合应变的演变。在应力破坏载荷下，纤维增强CMC的损伤演化和寿命分析中考虑了四种不同的随机载荷谱。建立了随机加载应力，频率，时间，界面剥离和氧化长度，纤维破坏概率以及应力断裂寿命之间的关系。随机加载应力和时间的影响，分析了纤维体积，基体裂纹间距，界面剥离能，界面剪切应力和复合材料应变温度，界面剥离和氧化长度，以及纤维失效概率随时间的变化。预测了SiC / SiC复合材料在恒定应力和随机载荷谱下的实验应力破裂应变和寿命。当随机加载应力，频率和温度增加时，应力断裂寿命以及界面完全脱粘和氧化的时间都会减少。预测了SiC / SiC复合材料在恒定应力和随机载荷谱下的实验应力破裂应变和寿命。当随机加载应力，频率和温度增加时，应力断裂寿命以及界面完全脱粘和氧化的时间都会减少。预测了SiC / SiC复合材料在恒定应力和随机载荷谱下的实验应力破裂应变和寿命。当随机加载应力，频率和温度增加时，应力断裂寿命以及界面完全脱粘和氧化的时间都会减少。