This work presents a cohesive interface model for predicting interlaminar failure of composite laminates under tension-tension fatigue loading. The model features improvements on previous formulations and utilizes four-integration-point elements, which offer several new advantages, while maintaining the merits of the previous single-integration-point elements. An element-based crack tip tracking algorithm is incorporated to confine fatigue damage to crack-tip elements only. A new local rate approach is proposed to ensure accurate integration of strain energy release rate from local elements. Furthermore, a dynamic fatigue characteristic length is proposed to offer a more accurate estimation of fatigue characteristic length in complex three-dimensional cases. Fatigue initiation is incorporated by using a strength reduction method, without changing the propagation characteristics. The numerical approach has been verified and validated using multiple cases and was then applied to fatigue damage development in open-hole laminates, where a good agreement between numerical analysis and experimental results was obtained.

这项工作提出了一种内聚界面模型，用于预测复合材料层合板在拉伸-拉伸疲劳载荷下的层间破坏。该模型对以前的公式进行了改进，并使用了四个积分点元素，这些元素提供了几个新的优势，同时保留了以前的单个积分点元素的优点。结合了基于元素的裂纹尖端跟踪算法，以将疲劳损伤仅限于裂纹尖端元素。提出了一种新的局部速率方法以确保应变能量从局部元素的释放速率的准确整合。此外，提出了动态疲劳特征长度，以便在复杂的三维情况下提供更准确的疲劳特征长度估计。通过使用强度降低方法来引入疲劳引发，而不改变传播特性。数值方法已经在多种情况下得到了验证和验证，然后被应用于裸眼层压板的疲劳损伤发展，在数值分析和实验结果之间取得了良好的一致性。