ABSTRACT

In this research, a thorough experimental and numerical study is conducted to investigate a novel application of the ultrasonic Lamb waves which is its capability to detect the coating disbond in a double-layer waveguide (aluminium-adhesive) and a triple-layer waveguide (aluminium-adhesive-coating). The experimental tests are set up and implemented to evaluate how the attenuation of Lamb waves is affected by the adhesive bonding beside the contribution of the coating layer to the behaviour of Lamb waves. In the presence of additive white Gaussian noise (AWGN), a range of important indices including energy index (EI), amplitude index (AI), pulse width index (PWI), and the time of flight index (ToFI) are worked out in association with the disbond length. It is inferred that a) even in the very noisy environment of 0 dB SNR, the Lamb waves are effectively able to identify debonding defects particularly using the EI, giving sensitivity rates 105% and 30% for triple-layer and double-layer, respectively; b) the contribution of adhesive to the absorption of the guided wave energy is 30%, 40%, and 50% in EI, AI, and PWI, respectively, corroborating the value of the features to distinguish the debonding between each layer of bonded structures.

摘要

在这项研究中，进行了彻底的实验和数值研究以研究超声波兰姆波的新应用，即它能够检测双层波导（铝粘合剂）和三层波导（铝-粘合剂涂层）。设置并实施实验测试以评估除了涂层对兰姆波行为的贡献之外，粘合剂粘合如何影响兰姆波的衰减。在存在加性高斯白噪声（AWGN）的情况下，计算出包括能量指数（EI）、幅度指数（AI）、脉宽指数（PWI）和飞行时间指数（ToFI）在内的一系列重要指标。与脱粘长度的关系。推断 a) 即使在 0 dB SNR 的非常嘈杂的环境中，兰姆波能够有效地识别剥离缺陷，尤其是使用 EI，三层和双层的灵敏度分别为 105% 和 30%；b) 在EI、AI和PWI中，粘合剂对导波能量吸收的贡献分别为30%、40%和50%，证实了区分每层粘合结构之间脱粘的特征值.