To solve the problem of fatigue life prediction of notched 3D woven composites, a novel fatigue life prediction method based on progressive damage and field intensity theory is proposed. By analyzing the initial loading process of 3D woven composite structure based on progressive damage method, the stress field when the fatigue damage develops gently and the dangerous area where the fatigue damage occurs first are obtained. Then combining with the concept of notch field intensity function, the failure criteria of composites and the three-dimensional space vector stress field intensity method, the fatigue damage degree field intensity of the fiber yarns in the dangerous area is analyzed and the most damaged fiber yarn is found. The fatigue life of the structure is calculated with the field intensity equivalent stress and the S-N curve of this fiber yarn. In order to verify the effectiveness of this method, the fatigue life of notched 3D woven composites under several stress levels is predicted and compared with the existing experimental data. The compared results show that the fatigue life prediction values are all within the two-fold error bounds of the experimental data, which are in good agreement with experimental results. Compared with the progressive damage fatigue life prediction method of woven composites, the prediction accuracy of the method proposed in this paper is improved by 31.5% on average, and the calculation efficiency is also greatly improved.

中文翻译：

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基于渐进损伤和场强的缺口3D编织复合材料疲劳寿命预测方法

针对缺口3D编织复合材料的疲劳寿命预测问题，提出了一种基于渐进损伤和场强理论的新型疲劳寿命预测方法。通过对基于渐进损伤法的3D编织复合结构初始加载过程的分析，得到疲劳损伤平缓发展时的应力场和疲劳损伤最先发生的危险区域。然后结合缺口场强函数的概念、复合材料的失效判据和三维空间矢量应力场强法，对危险区域内纤维纱的疲劳损伤程度场强进行分析，得出损伤最严重的纤维纱。被发现。通过场强等效应力和该纤维纱的SN曲线计算结构的疲劳寿命。为了验证该方法的有效性，预测了多个应力水平下缺口 3D 编织复合材料的疲劳寿命，并与现有的实验数据进行了比较。对比结果表明，疲劳寿命预测值均在实验数据的两倍误差范围内，与实验结果吻合较好。与编织复合材料渐进式损伤疲劳寿命预测方法相比，本文提出的方法的预测精度平均提高了31.5%，计算效率也大大提高。预测了多个应力水平下带缺口的 3D 编织复合材料的疲劳寿命，并与现有的实验数据进行了比较。对比结果表明，疲劳寿命预测值均在实验数据的两倍误差范围内，与实验结果吻合较好。与编织复合材料渐进式损伤疲劳寿命预测方法相比，本文提出的方法的预测精度平均提高了31.5%，计算效率也有较大提高。预测了多个应力水平下带缺口的 3D 编织复合材料的疲劳寿命，并与现有的实验数据进行了比较。对比结果表明，疲劳寿命预测值均在实验数据的两倍误差范围内，与实验结果吻合较好。与编织复合材料渐进式损伤疲劳寿命预测方法相比，本文提出的方法的预测精度平均提高了31.5%，计算效率也大大提高。