The fatigue life of plain-woven SiC/SiC composites was predicted with the multi-scale method by combining the micromechanical model with the mesoscale finite element model. The micromechanical constitutive relationship of yarns under variable amplitude loading was derived, and the mesoscale finite element model was established by choosing the minimum repeatable unit as the unit cell. The degradation of interface shear stress was obtained by fitting the secant modulus of hysteresis loop, and the fiber random fracture model based on the global load sharing model was adopted to simulate the fatigue failure of the yarns. To improve the prediction speed of fatigue life, the number of fatigue cycles increases exponentially. The fatigue life of plain-woven SiC/SiC composites predicted with the multi-scale method are in good agreement with the experimental results.

通过将微机械模型与中尺度有限元模型相结合，采用多尺度方法预测了平纹SiC / SiC复合材料的疲劳寿命。推导了可变振幅载荷下纱线的微机械本构关系，并以最小可重复单元为单位建立了中尺度有限元模型。通过拟合磁滞回线的割线模量，获得界面剪应力的降级，并采用基于全局载荷分担模型的纤维随机断裂模型来模拟纱线的疲劳破坏。为了提高疲劳寿命的预测速度，疲劳循环数呈指数增长。