Huang Ruochen, Lu Mingyang, Chen Ziqi, Yin Wuliang
School of Electrical and Electronic Engineering, University of Manchester, Manchester M13 9PL, UK.
Sensors (Basel). 2021 Dec 28;22(1):201. doi: 10.3390/s22010201.
Alternating current field measurement (ACFM) testing is one of the promising techniques in the field of non-destructive testing with advantages of the non-contact capability and the reduction of lift-off effects. In this paper, a novel crack detection approach was proposed to reduce the effect of the angled crack (cack orientation) by using rotated ACFM techniques. The sensor probe is composed of an excitation coil and two receiving coils. Two receiving coils are orthogonally placed in the center of the excitation coil where the magnetic field is measured. It was found that the change of the x component and the peak value of the z component of the magnetic field when the sensor probe rotates around a crack followed a sine wave shape. A customized accelerated finite element method solver programmed in MATLAB was adopted to simulate the performance of the designed sensor probe which could significantly improve the computation efficiency due to the small crack perturbation. The experiments were also carried out to validate the simulations. It was found that the ratio between the z and x components of the magnetic field remained stable under various rotation angles. It showed the potential to estimate the depth of the crack from the ratio detected by combining the magnetic fields from both receiving coils (i.e., the x and z components of the magnetic field) using the rotated ACFM technique.
交变电流场测量（ACFM）检测是无损检测领域中一项很有前景的技术，具有非接触能力和减少提离效应的优点。本文提出了一种新颖的裂纹检测方法，通过使用旋转ACFM技术来减少斜裂纹（裂纹取向）的影响。传感器探头由一个激励线圈和两个接收线圈组成。两个接收线圈正交放置在激励线圈的中心，用于测量磁场。研究发现，当传感器探头围绕裂纹旋转时，磁场的x分量变化和z分量峰值呈正弦波形状。采用在MATLAB中编程的定制加速有限元方法求解器来模拟设计的传感器探头的性能，由于裂纹扰动较小，该求解器可显著提高计算效率。还进行了实验以验证模拟结果。结果发现，在各种旋转角度下，磁场的z分量与x分量之比保持稳定。这表明使用旋转ACFM技术，通过结合来自两个接收线圈的磁场（即磁场的x分量和z分量）检测到的比率来估计裂纹深度具有潜力。
