Hayashi Takahiro, Murase Morimasa, Salim Muhammad Nor
Faculty of Engineering, Nagoya Institute of Technology, Gokiso, Showa, Nagoya, Japan.
J Acoust Soc Am. 2009 Sep;126(3):1101-6. doi: 10.1121/1.3177268.
Guided waves have been effectively used for rapid inspections of plates and pipes. However, the guided-wave technique is not generally used for measuring the remaining thickness in a plate and a pipe due to the difficulties in guided-wave motion. Instead, time-consuming and costly direct contact thickness measurements are still used in practice. This study describes a thickness measurement technique using the A0 mode of a Lamb wave generated by a laser source. A finite element analysis of Lamb wave revealed that this mode propagates with small reflections and mode conversions at a rounded shallow defect and has larger amplitude at thinner regions. Using these characteristics, it is experimentally demonstrated that the distributions of plate thickness were obtained from the amplitude of A0 mode generated by a scanning laser source and received by an angle-beam transducer. The resulting distribution images were obtained at extremely high speed compared to the conventional thickness measurements.
导波已被有效地用于板材和管道的快速检测。然而，由于导波传播存在困难，导波技术一般不用于测量板材和管道的剩余厚度。相反，耗时且昂贵的直接接触式厚度测量在实际中仍被使用。本研究描述了一种利用激光源产生的兰姆波A0模式进行厚度测量的技术。对兰姆波的有限元分析表明，该模式在圆形浅缺陷处传播时反射和模式转换较小，且在较薄区域具有较大的振幅。利用这些特性，通过实验证明，可以从扫描激光源产生并由角波束换能器接收的A0模式的振幅获得板材厚度分布。与传统厚度测量相比，最终获得的分布图像速度极快。
