Defect Imaging with Guided Waves Propagating in a Long Range
Defect Imaging with Guided Waves Propagating in a Long Range
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利用长距离传播的导波进行缺陷成像
DOI：
10.1299/kikaia.72.1941
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发表时间：
2006
期刊：
影响因子：
--
通讯作者：
M. Murase
中科院分区：
文献类型：
--
作者：
T. Hayashi;M. Nagao;M. Murase
导波管道检测作为一种有效的筛选技术，使我们能够检测几十米的管道，被寄予厚望。虽然在实际检测现场广泛引入的检测设备采用易于使用的轴对称模式，作者已经开发了使用非轴对称模式以及缺陷成像技术。在我们以前的论文中，缺陷图像显示在距离传感器仅1.2米的短范围内。因此，在这项研究中，长传播的缺陷图像的影响进行了讨论。远距离成像实验上使用源信号和它们在4米长的管道的两个边缘之间的多次反射，而不是来自缺陷的反射波。在实验研究中，在远场图像表现出很大的退化。导波传播的计算机模拟表明，一个主要的原因是一个实际的管道和理论的频散曲线之间的差异。为了减少退化，通过忽略具有较大相速度差异的较高模式来获得图像。结果，在高达约20米的正确位置获得了图像。
Pipe inspection with guided waves is highly expected as an efficient screening technique that enables us to inspect a few dozen meters of a pipe. Although inspection equipments widely introduced in a practical inspection site adopt easy-to-use axisymmetric modes, authors have developed defect imaging technique using non-axisymmetric modes as well. In our previous paper, defect images were shown in short range of only 1.2 meters away from transducers. In this study, therefore, effects of long propagation to defect images are discussed. Long range imaging was experimentally done using source signals and their multiple reflections between both edges of a 4-meter-long pipe, instead of reflected waves from defects. In the experimental investigation, large degradation of images was shown in far field. A computer simulation of guided wave propagation reveals that a major reason of the degradation is the difference between dispersion curves for an actual pipe and theoretical ones. To reduce the degradation, images were obtained by neglecting higher modes with larger differences in phase velocity. As a result, images were obtained in correct location up to about 20 meters.