In this study, the high-cycle and very-high-cycle fatigue properties of carbon fiber reinforced plastic (CFRP)-aramid honeycomb sandwich structure, which is a commonly used structure in aviation industry, are examined under two different core directions using the ultrasonic three-point bending fatigue test. Further, the fatigue failure modes and damage mechanism of the structure are revealed. The results show that the fatigue stiffness degradation curve of the honeycomb sandwich structure exhibits three different trends: continuous decline, two horizontal regions and two reduction regions, and two horizontal regions and one reduction region. The shape of the stiffness degradation curve is affected by the direction of core. The S-N curve presents a double-linear decline feature, and there is no traditional fatigue limit. The fatigue life of the specimen is related to the type of stiffness degradation. The optical microscopy images show that the main failure modes of specimens are core wrinkles, core cracks, and face delamination. Overall, based on the stiffness degradation curve, failure modes, and real-time images of the test specimens, the damage evolution process and the corresponding mechanism of the honeycomb sandwich structure are analyzed to conclude that the core has multi-point failure damage characteristics.

在这项研究中，使用超声波在两个不同的芯方向下检查了航空工业中常用的碳纤维增强塑料 (CFRP)-芳纶蜂窝夹层结构的高周和超高周疲劳性能。三点弯曲疲劳试验。进一步揭示了结构的疲劳破坏模式和损伤机制。结果表明，蜂窝夹层结构的疲劳刚度退化曲线呈现出三种不同的趋势：连续下降、两横二折区、两横一折区。刚度退化曲线的形状受芯方向的影响。SN曲线呈现双线性下降特征，没有传统的疲劳极限。试样的疲劳寿命与刚度退化的类型有关。光学显微镜图像显示，试样的主要失效模式为芯部皱纹、芯部裂纹和表面分层。总体而言，基于试件的刚度退化曲线、破坏模式和实时图像，分析了蜂窝夹层结构的损伤演化过程和相应机制，得出芯部具有多点破坏损伤特征的结论。