Abstract A fracture mechanics model is proposed for the prediction of the critical damage state corresponding to tension-tension fatigue failure of unidirectional fibre composites. The critical damage state is characterized by the development of longitudinal splitting cracks, enabling isolated damage zones with broken fibres to link up. The critical damage state can be expressed in terms of the size of damage zones with broken fibres. The critical damage zone size depends on the maximum applied cyclic stress level, the geometry of the splitting pattern and on the Mode II fracture energy of the composite. The model was used for predicting the critical damage size of a glass fibre composites subjected to cyclic loading. In a study reported in the literature, the damage zone size was determined experimentally by X-ray tomography just prior to fatigue failure. A good agreement was found between the predicted and reported damage zone sizes. Moreover, the reported failure involved longitudinal splitting in accordance with the model.

中文翻译：

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控制单向纤维复合材料拉拉疲劳寿命的临界损伤状态

摘要 提出了一种断裂力学模型，用于预测单向纤维复合材料拉拉疲劳失效对应的临界损伤状态。临界损伤状态的特点是纵向分裂裂纹的发展，使具有断裂纤维的孤立损伤区能够连接起来。临界损伤状态可以用纤维断裂的损伤区域的大小来表示。临界损伤区的大小取决于施加的最大循环应力水平、分裂模式的几何形状和复合材料的 II 型断裂能。该模型用于预测玻璃纤维复合材料在循环载荷作用下的临界损伤尺寸。在文献报道的一项研究中，损伤区的大小是在疲劳失效前通过 X 射线断层扫描实验确定的。在预测的和报告的损伤区域大小之间发现了很好的一致性。此外，报告的故障涉及根据模型纵向分裂。