Ji Dingcheng, Gao Fei, Hua Jiadong, Lin Jing
School of Reliability and Systems Engineering, Beihang University, Xueyuan Road No. 37, Haidian District, Beijing, China.
School of Reliability and Systems Engineering, Beihang University, Xueyuan Road No. 37, Haidian District, Beijing, China; Ningbo Institution of Technology (NIT), Beihang University, Ningbo 315832, China.
Ultrasonics. 2023 Sep;134:107101. doi: 10.1016/j.ultras.2023.107101. Epub 2023 Jul 6.
Crack damage is one of the significant factors that may accumulate at the stress concentration area of engineering structures and cause catastrophic accidents. In this paper, we proposed a novel approach to identify the crack location and size by exploiting the reflections and diffractions of Lamb waves. The interaction mechanism between the crack and Lamb wave has been analyzed thoroughly, our analysis of the interaction between the crack and Lamb wave revealed that both reflections and diffractions carry valuable damage information that reflects the size and orientation of the crack. As the interaction coefficients between these two components and the crack are different, there are supposed to exist differences between them in the amplitude value. We implemented a threshold to classify the signals received from all paths into two groups: reflections and diffractions. Then we constructed an overcomplete dictionary of waveforms corresponding to different propagation distances to extract the damage information. Using sparse decomposition, the received signals were mapped to their corresponding propagation distances without the use of baseline signals. The diffractions allow us to determine the crack's tip points, while the reflections provide information about the edge points. The kinked crack's size and orientation were visualized based on the time-domain signals acquired in our experiment. We provided a comprehensive description of our algorithm and verified it through numerical simulation and experimental data. Our results show high agreement with actual cracks, demonstrating the efficacy of our proposed method.
裂纹损伤是可能在工程结构的应力集中区域累积并导致灾难性事故的重要因素之一。在本文中，我们提出了一种利用兰姆波的反射和衍射来识别裂纹位置和尺寸的新方法。对裂纹与兰姆波之间的相互作用机制进行了深入分析，我们对裂纹与兰姆波相互作用的分析表明，反射和衍射都携带了反映裂纹尺寸和方向的有价值的损伤信息。由于这两个分量与裂纹之间的相互作用系数不同，它们在幅值上应该存在差异。我们设置了一个阈值，将从所有路径接收到的信号分为两组：反射和衍射。然后我们构建了一个对应于不同传播距离的波形过完备字典来提取损伤信息。使用稀疏分解，在不使用基线信号的情况下将接收到的信号映射到它们相应的传播距离。衍射使我们能够确定裂纹的尖端点，而反射提供有关边缘点的信息。基于我们实验中获取的时域信号，直观显示了扭折裂纹的尺寸和方向。我们对算法进行了全面描述，并通过数值模拟和实验数据进行了验证。我们的结果与实际裂纹高度吻合，证明了我们所提方法的有效性。
