Abstract

The influences of excitation current on the evaluation of the corrosion with a cylindrical shape in a semi-infinite plate are presented in this paper. First, axi-symmetric model of the cylindrical coil above the corroded plate is established and an analytical solution to the surface magnetic field is derived by means of the truncated region eigenfunction expansion method (TREE). Then, the effect of the excitation current frequency and amplitude on the surface magnetic field is investigated and quantitatively evaluated. It is found that the radial magnetic induction intensity increases as the excitation current frequency increases, whereas the axial magnetic induction intensity decreases. The excitation current amplitude is proportional to the radial and axial magnetic induction intensities and does not affect the phase of magnetic induction intensity. As a result, the influence node for detecting the radius and the hollow depth for detecting the hidden depth are obviously dependent on the excitation current frequency in terms of the butterfly-shaped graph. The calculation results are in good agreement with the numerical simulation, showing that the developed model can be used to predict the optimal excitation current frequency. This work indicates that an appropriate excitation current frequency, such as f = 500 Hz, can improve the characteristic parameter resolution for detecting the corrosion radius. For the detection of hidden depth, the lower excitation current frequency, such as f = 100 Hz, can amplify the defect phenomenon and improve the detection accuracy. It is not only helpful to develop the analytical model for the surface magnetic field, but also to optimise the parameters of the test device.

中文翻译：

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基于表面磁场分析模型的励磁电流频率和幅度对腐蚀评估的影响

摘要

提出了励磁电流对半无限圆柱状腐蚀评估的影响。首先，建立了锈蚀板上方圆柱线圈的轴对称模型，并通过截断区域特征函数展开法（TREE）推导了表面磁场的解析解。然后，研究并定量评估了励磁电流频率和幅度对表面磁场的影响。已经发现，随着励磁电流频率的增加，径向磁感应强度增加，而轴向磁感应强度减小。励磁电流幅度与径向和轴向磁感应强度成正比，并且不影响磁感应强度的相位。结果，用于检测半径的影响节点和用于检测隐藏深度的凹陷深度显然取决于蝶形图的励磁电流频率。计算结果与数值模拟吻合良好，表明所开发的模型可用于预测最佳励磁电流频率。这项工作表明一个适当的励磁电流频率，例如 计算结果与数值模拟吻合良好，表明所开发的模型可用于预测最佳励磁电流频率。这项工作表明一个适当的励磁电流频率，例如 计算结果与数值模拟吻合良好，表明所开发的模型可用于预测最佳励磁电流频率。这项工作表明一个适当的励磁电流频率，例如f = 500 Hz，可以提高用于检测腐蚀半径的特征参数分辨率。对于隐藏深度的检测，较低的激励电流频率（例如f = 100 Hz）可以放大缺陷现象并提高检测精度。开发表面磁场的分析模型不仅有帮助，而且有助于优化测试设备的参数。