单向碳/碳复合材料拉-拉疲劳寿命及剩余强度预测模型

基于预测单向复合材料纵向拉伸强度的随机核模型，引入纤维单丝剩余强度二参数Weibull模型及纤维单丝与基体界面剩余强度模型，研究建立了单向复合材料纵向拉-拉疲劳寿命及剩余强度的预测模型。对经过一定次数拉-拉疲劳载荷循环后的纤维束抽取其纤维单丝进行剩余强度拉伸试验，建立了纤维单丝剩余强度的二参数Weibull模型，测试单向碳/碳（C/C）复合材料的纤维与基体界面强度。通过单向C/C复合材料算例分析表明，92.5%、90.6%和87.5%应力水平下对数预测寿命与对数试验寿命比值分别为0.79、1.00和1.11，表明所建立的寿命预测模型用于预测单向C/C复合材料疲劳寿命是可行的；纵向拉伸剩余强度预测值与试验值误差在10%以内，吻合较好，表明所提出的剩余强度预测模型具有较高的精度。

Model for predicting tension-tension fatigue life and residual strength of unidirectional carbon/carbon composites

Based on the random crack core theory and model for predicting the longitudinal tensile strengths of unidirectional composites, the Weibull model describing residual strength distribution of single fiber and the residual strength model of fiber-matrix interfaces were brought in for building the prediction model which can predict tension-tension fatigue life and residual strength of unidirectional composites. The residual strength test of the carbon fiber extracted from the fibers yarn after cyclic tensile fatigue loading was carried out. The two parameters Weibull model of the residual strength of carbon fiber was established. The fiber-matrix interface strength of unidirectional carbon/carbon(C/C) composites was tested. The unidirectional C/C composites analysis results show that the ratios of prediction logarithmic life to test logarithmic life are 0.79, 1.00 and 1.11 under 92.5%, 90.6% and 87.5% stress level, respectively, which indicates that the life prediction model is feasible for fatigue life prediction of unidirectional C/C composites. The error between the predicted value and the experimental value of residual strength is within 10%, which demonstrates that the prediction model of residual strength has high precision.