In order to isolate the influence of ply orientation on the mode I fatigue delamination propagation behavior of carbon fiber reinforced composite laminates, multidirectional laminates with the same overall stiffness are designed while three different interfaces (0//0, 45//45, and 90//90), which can avoid the coupling effect of remote plies. Test results show that the fatigue delamination behavior is obviously affected by the interface angle. In addition, a novel and simple method for determining the fatigue delamination resistance is proposed. The measured fatigue delamination resistance is lower than the quasi-static one for all interfaces. The specimen with 45//45 interface exhibits more significant delamination resistance, whereas the delamination resistances of specimens with 0/0 and 90//90 interfaces are similar, which is consistent with the phenomenon of more bridging fibers accompanying in the delamination process of 45//45 interface. In order to consider the effect of fiber bridging and reduce the dispersion of the data, experimental data are further processed using a normalized model considering the effect of fiber bridging. The normalized results can be characterized by a single curve, suggesting that the normalized model is effective in describing the fatigue delamination behavior in the presence of fiber bridging.

中文翻译：

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具有相同整体刚度的多向层合板的模式 I 疲劳分层增长行为和模型


为了隔离层取向对碳纤维增强复合材料层合板I型疲劳分层扩展行为的影响，设计了具有相同整体刚度的多向层合板，同时具有3个不同的界面（0//0、45//45和90//90），可以避免远程层的耦合效应。试验结果表明，疲劳分层行为明显受界面角的影响。此外，还提出了一种新颖简单的疲劳分层电阻测定方法。测得的疲劳分层阻力低于所有界面的准静态阻力。具有 45//45 界面的试件表现出更显著的分层阻力，而具有 0/0 和 90//90 界面的试件的分层阻力相似，这与 45//45 界面分层过程中伴随桥接纤维较多的现象一致。为了考虑纤维桥接的影响并减少数据的离散性，使用考虑纤维桥接影响的归一化模型对实验数据进行了进一步处理。归一化结果可以用一条曲线来表征，这表明归一化模型可以有效地描述存在纤维桥接时的疲劳分层行为。