Abstract This paper introduces a novel approach to crack detection and localization in a pipeline transporting fluid under high pressure. From acoustic emission signals acquired by two R15i-AST sensors at two ends of a fluid pipeline, the proposed method scans peaks in the individual signal channels in the time-frequency domain and filters out noise to obtain acoustic emission events. Subsequently, adjacent events are combined into grouped events, and these are picked and paired together on two sensor channels to localize emission sources using the time difference of arrival technique. To improve the location accuracy, the mechanism only determines the arrival time of Rayleigh waves with a similar frequency in event pairs. Furthermore, the Rayleigh wave velocity is calibrated by a pencil lead breaking procedure. Additionally, false emission sources are eliminated by considering the wave energy attenuation characteristics in their propagation path. After locating the emission sources, the approach observes their distribution according to the position and time of occurrence. The variation in acoustic emission activity against applied load, which is established by counting the returned sources, can indicate irregular structural changes in a material. The location of the structural change can be surmised by the emission source distribution and density according to the position along the pipeline. Experimental results show that the proposed method correctly diagnoses faults in the considered pipeline from acoustic emission signals, whereas a conventional approach (performed by detecting hits with a threshold) inaccurately localizes acoustic emission sources and imprecisely exposes signs of abnormal structural transformations.

中文翻译：

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基于声发射信号的流体管道裂纹检测与定位

摘要 本文介绍了一种在高压下输送流体的管道中裂纹检测和定位的新方法。该方法从流体管道两端的两个R15i-AST传感器获取的声发射信号中，在时频域扫描单个信号通道中的峰值并滤除噪声以获得声发射事件。随后，相邻事件被组合成分组事件，这些事件在两个传感器通道上被挑选和配对在一起，以使用到达时间差技术定位发射源。为了提高定位精度，该机制仅确定事件对中频率相似的瑞利波的到达时间。此外，瑞利波速度通过铅笔芯折断程序进行校准。此外，通过考虑其传播路径中的波能量衰减特性来消除虚假发射源。在定位排放源后，该方法根据发生的位置和时间观察它们的分布。声发射活动随外加载荷的变化（通过对返回源进行计数确定）可以表明材料中的不规则结构变化。根据管道沿线位置的排放源分布和密度，可以推测结构变化的位置。实验结果表明，所提出的方法从声发射信号正确地诊断出所考虑管道中的故障，