Decoupling the Influence of Permeability and Conductivity in Pulsed Eddy-Current Measurements
Decoupling the Influence of Permeability and Conductivity in Pulsed Eddy-Current Measurements
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DOI：
10.1109/tmag.2012.2225634
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发表时间：
2013-03-01
影响因子：
2.1
通讯作者：
Tian, Gui Yun
中科院分区：
文献类型：
--
作者：
Adewale, Ibukun Dapo;Tian, Gui Yun
电涡流传感器广泛应用于工业无损检测和结构健康监测。它之所以被广泛接受，主要是因为它具有对恶劣环境的高容忍度、低成本和高带宽。它的可变脉冲涡流(PEC)提供了更多的测试材料的深度信息，可用于升空测量(位移和涂层厚度测量)、缺陷测量和材料表征。然而，PEC传感器容易由于一种称为电跳动(ERO)的现象而产生测量误差，这种现象被归因于测试材料的不均匀性。因此，本文的主要目的是研究样品的电磁特性(磁导率和电导率)对ERO的贡献，以期将这两种特性的影响分开。研究中同时进行了时间域和频域分析，即：瞬时响应、差分归一化响应、震级谱和归一化震级谱。本文揭示了电导效应在暂态响应的上升沿非常显著，从而改变了频域的频谱模式，而磁导率效应在暂态响应的稳定阶段起主导作用，因此可以通过归一化来抑制或减小这种影响，表明这只是一个幅度变化。
Eddy-current (EC) sensors are widely used in the industry for nondestructive evaluation (NDE) and structural health monitoring (SHM). It has this wide acceptance mainly because it has high tolerance to harsh environments, low cost, and high bandwidth. Its variant pulsed eddy current (PEC) provides even more depth information of test materials, which can be applied in liftoff measurement (displacement and coating thickness measurement), defect measurement, and material characterization. However, PEC sensors are prone to measurement errors due to a phenomenon called electrical runout (ERO), which is attributed to the inhomogeneity of the test material. The main thrust of this paper is to investigate, therefore, the contributions of the electromagnetic properties (permeability and conductivity) of the sample to ERO with a view to separate the influence of these two properties. Both time-domain and frequency-domain analyses are carried out in this investigation viz-a-viz: transient response, differential normalized response, magnitude spectrum, and normalized magnitude spectrum. This paper reveals that conductivity effects are prominent in the rising edge of the transient response, hence, changing the spectral pattern in the frequency domain while permeability effects dominate in the stable phase of the transient response, thus this effect can be suppressed or reduced by normalization showing that it is only an amplitude change.