Nondestructive testing (NDT) for ferromagnetic material under motion condition is a challenging topic, because the distribution of the magnetic fields inside the ferromagnetic material is more complicated due to motion-induced eddy current (MIEC) and ferromagnetic material magnetization. Therefore, a fast, accurate, and automatic NDT technique for quantitative detection of crack in the moving ferromagnetic material is an urgent issue. Currently, the pulsed eddy current (PEC) technique is widely applied in quantitative crack characterization in metals; however, the literature focus on the investigation of the velocity influence on PEC is rare. This article performs a deep investigation on the velocity effect of PEC technique by numerical simulation and experiments, and the relationships of speed and PEC signal are discovered. The results show that the velocity effect can change the baseline value of the detection signal in the PEC detection system. Moreover, the crack location, width, and depth can be characterized by PEC with high speed when crack appears in the high-level stage of the excitation signal, and in contrast to static PEC testing, motion detection has a stronger capability to characterize the crack depths. Based on the results, it is beneficial to propose a new high-speed inspection technique for crack characterization in ferromagnetic material components, such as rotating metal components, pipelines, and rail tracks.

中文翻译：

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脉冲涡流检测铁磁材料裂纹的速度效应研究

在运动条件下对铁磁材料进行无损检测 (NDT) 是一个具有挑战性的课题，因为由于运动感应涡流 (MIEC) 和铁磁材料磁化，铁磁材料内部的磁场分布更加复杂。因此，一种快速、准确、自动的无损检测技术用于定量检测运动铁磁材料中的裂纹是一个紧迫的问题。目前，脉冲涡流（PEC）技术广泛应用于金属裂纹的定量表征；然而，关于速度对 PEC 影响的研究的文献很少。本文通过数值模拟和实验对PEC技术的速度效应进行了深入研究，发现了速度与PEC信号的关系。结果表明，速度效应可以改变PEC检测系统中检测信号的基线值。此外，当裂纹出现在激励信号的高电平阶段时，PEC可以高速表征裂纹位置、宽度和深度，并且与静态PEC测试相比，运动检测具有更强的裂纹表征能力深度。基于这些结果，有利于提出一种新的高速检测技术，用于铁磁材料部件（如旋转金属部件、管道和铁轨）中的裂纹表征。当裂纹出现在激励信号的高电平阶段时，PEC可以高速表征深度和深度，与静态PEC测试相比，运动检测具有更强的表征裂纹深度的能力。基于这些结果，有利于提出一种新的高速检测技术，用于铁磁材料部件（如旋转金属部件、管道和铁轨）中的裂纹表征。当裂纹出现在激励信号的高电平阶段时，PEC可以高速表征深度和深度，与静态PEC测试相比，运动检测具有更强的表征裂纹深度的能力。基于这些结果，有利于提出一种新的高速检测技术，用于铁磁材料部件（如旋转金属部件、管道和铁轨）中的裂纹表征。