Carbon fibre‐reinforced polymers (CFRPs) are now widely used for high‐performance fields such as aircraft structures. On average, these structural components are subjected with more than 10⁸ cycles during their lifetime. To make full use of the mechanical performance of CFRP, the fatigue behaviour needs to be well studied. Nevertheless, at present, fatigue behaviour and failure mechanisms of CFRP under hygrothermal environment are not sufficiently investigated. To obtain comprehensive knowledge about fatigue behaviour and failure mechanisms of CFRP, hygrothermal tests and ultrasonic three‐point bending fatigue experiments are designed. Besides, a damage variable is proposed as the function of stiffness to evaluate the fatigue degradation of the composite. A nonlinear continuum damage mechanics (CDM) model is compared with three models and employed for fatigue damage evolution under cyclic loading. Compared with the other three models, the experimental results show a better consistency between the result of the CDM model and the measured damage. Meanwhile, the damage variable expresses the damage state of the composite effectively. The damage variable and the CDM model provide a reference for fatigue characterization analysis and further life prediction of CFRP.

中文翻译：

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基于连续损伤力学模型的湿热环境下碳纤维布疲劳表征研究

碳纤维增强聚合物（CFRP）现在被广泛用于飞机结构等高性能领域。平均而言，这些结构部件要承受超过10 ⁸在他们的一生中循环。为了充分利用CFRP的机械性能，需要对疲劳性能进行深入研究。然而，目前，关于湿热环境下CFRP的疲劳行为和破坏机理还没有得到足够的研究。为了获得有关CFRP疲劳行为和破坏机理的全面知识，设计了湿热试验和超声三点弯曲疲劳试验。此外，提出了损伤变量作为刚度的函数，以评估复合材料的疲劳降解。将非线性连续损伤力学（CDM）模型与三种模型进行比较，并用于循环载荷下的疲劳损伤演化。与其他三个模型相比，实验结果表明，CDM模型的结果与测得的损伤之间具有更好的一致性。同时，损伤变量有效地表达了复合材料的损伤状态。损伤变量和CDM模型为CFRP的疲劳特性分析和进一步的寿命预测提供参考。