Abstract In this paper, a disbond detection method for aeronautical honeycomb sandwich composites using Lamb waves is proposed. Due to the scale mismatching between the wavelength and the panel thickness, the honeycomb core cannot be homogenized to a single layer medium in wave propagating model with short wavelength. Waves can leak through the honeycomb core and be reflected back and forth between the top and bottom interfaces, which forms the coda waves inside the structure. As direct waves and coda waves have distinct propagation behaviors, the corresponding amplitude and velocity features exhibit a different evolution trend varying accordingly to disbond sizes and interface positions. With the experimental pre-knowledge of wave velocities, the local power spectrum density (LPSD) is employed for energy dissipation representation and a windowed cross-correlation method is addressed for time delay estimation, thereby providing quantitative identification for disbond assessment. By judging the damage feature evolution trends of direct and coda waves, disbond underneath both skins can be further detected. Hence, classifying disbond with one-side accessing measurements is realizable. The experiment was carried out on a honeycomb sandwich composite plate cut from the Airbus A330 elevator. Two pairs of PZTs were bonded symmetrically on the skins to illustrate the disbond characterizing method. The result verified the sensitivity of direct and coda waves to the disbond size and the interface position. Instructions for texting scheme and feature extraction in honeycomb structure health monitoring is provided accordingly.

中文翻译：

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兰姆波及其尾波在航空蜂窝复合材料夹层脱粘检测中的应用

摘要 本文提出了一种基于兰姆波的航空蜂窝夹层复合材料脱粘检测方法。由于波长与面板厚度的尺度不匹配，在短波长波传播模型中，蜂窝芯无法均匀化为单层介质。波可以通过蜂窝芯泄漏并在顶部和底部界面之间来回反射，从而在结构内部形成尾波。由于直达波和尾波具有不同的传播行为，相应的幅度和速度特征表现出不同的演化趋势，相应地随着脱粘尺寸和界面位置而变化。随着波速的实验预知，局部功率谱密度 (LPSD) 用于能量耗散表示，并采用加窗互相关方法进行时间延迟估计，从而为脱粘评估提供定量识别。通过判断直达波和尾波的损伤特征演变趋势，可以进一步检测到两种表皮下的脱粘。因此，可以通过单侧访问测量对脱粘进行分类。该实验是在从空中客车 A330 升降机上切下的蜂窝夹层复合板上进行的。两对 PZT 对称地粘合在皮肤上以说明脱粘表征方法。结果验证了直达波和尾波对脱粘尺寸和界面位置的敏感性。