A practical method for predicting fatigue life of the main spar with wrinkle defects in a wind turbine blade is presented in this paper. First, the effect of different wrinkle geometry on stiffness in a composite laminate is quantified. Then, the model of intrinsic dissipated energy is proposed to determine the fatigue limit rapidly. A fatigue life prediction model containing unknown parameters is developed by introducing intrinsic dissipated energy to characterize stiffness degradation of the main spar laminate with wrinkle defects. The specimens with different wrinkle geometry are subjected to fatigue tests, monitored with an infrared thermography system to obtain experimental data. After determining the unknown parameters of the developed model, the S-N curves of specimens are evaluated in a relatively short time. The predicted fatigue life is within the 95% confidence interval of lifetime obtained by the traditional tests, which suggests the developed model is accurate. This work is suitable for fatigue life prediction of main spar with different wrinkle defects.

中文翻译：

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风力机叶片含皱缺陷主梁疲劳寿命预测

本文提出了一种预测风力涡轮机叶片中具有皱纹缺陷的主梁疲劳寿命的实用方法。首先，量化不同褶皱几何形状对复合层压板刚度的影响。然后，提出了固有耗散能量模型来快速确定疲劳极限。通过引入固有耗散能量来表征具有皱纹缺陷的主翼梁层压板的刚度退化，开发了包含未知参数的疲劳寿命预测模型。具有不同皱纹几何形状的试样进行疲劳测试，用红外热成像系统监测以获得实验数据。在确定所开发模型的未知参数后，可以在相对较短的时间内评估样本的 SN 曲线。预测的疲劳寿命在传统测试获得的寿命的 95% 置信区间内，这表明开发的模型是准确的。该工作适用于具有不同皱纹缺陷的主梁的疲劳寿命预测。