Huan Qiang, Chen Mingtong, Su Zhongqing, Li Faxin
LTCS and College of Engineering, Peking University, Beijing 100871, China; Center for Applied Physics and Technology, Peking University, Beijing, China.
Department of Mechanical Engineering, The Hong Kong Polytechnic University, Hong Kong Special Administrative Region.
Ultrasonics. 2019 Aug;97:29-37. doi: 10.1016/j.ultras.2019.04.005. Epub 2019 Apr 29.
Guided wave based structural health monitoring (SHM) has been regarded as an effective tool to detect the early damage in large structures and thus avoid possible catastrophic failure. In recent years, Lamb wave phased array SHM technology had been intensively investigated while the inherent multi-mode and dispersive characteristic of Lamb waves limits its further applications. In comparison, the fundamental shear horizontal (SH) wave is non-dispersive with uncoupled displacements and thus more promising for defect detection. In this work, we proposed an SH wave linear phased array SHM system based on our recently proposed omni-directional SH wave piezoelectric transducer (OSH-PT). Firstly, the working principle of the phased array system was presented and the total focusing method (TFM) was employed for imaging. Then the SH wave mode generated by the OSH-PT was confirmed in a defect-free plate. Finally, experiments were carried out to examine the performances of this SHM system. Results showed that the proposed system can detect a through-thickness hole as small as 2 mm in diameter with the location error only about 6.3 mm. Moreover, the proposed phased array system can also detect multi-defects. Due to its low working frequency and thus low attenuation, the proposed phased array system is capable of monitoring large structures. This work will lay the foundations of SH wave based phased array SHM.
基于导波的结构健康监测（SHM）被视为检测大型结构早期损伤并避免可能的灾难性故障的有效工具。近年来，兰姆波相控阵SHM技术得到了深入研究，但兰姆波固有的多模和色散特性限制了其进一步应用。相比之下，基本水平剪切（SH）波是非色散的，位移不耦合，因此在缺陷检测方面更具潜力。在这项工作中，我们基于最近提出的全向SH波压电换能器（OSH-PT）提出了一种SH波线性相控阵SHM系统。首先，介绍了相控阵系统的工作原理，并采用全聚焦方法（TFM）进行成像。然后在无缺陷板中确认了OSH-PT产生的SH波模式。最后，进行实验以检验该SHM系统的性能。结果表明，所提出的系统能够检测直径小至2毫米的贯穿厚度孔，定位误差仅约6.3毫米。此外，所提出的相控阵系统还能检测多个缺陷。由于其工作频率低，衰减也低，所提出的相控阵系统能够监测大型结构。这项工作将为基于SH波的相控阵SHM奠定基础。
