BQ-06 Optimal Design of Dual Induction Eddy Current Probe for Vibration Suppression
Creators: Kota Matsushima
Daigo Kosaka
Yuji Kumakura
Publisher: name: IEEE
Year: 2025

In comparison to other non-destructive testing methods, eddy current testing (ECT) can detect minute surface defects that occur during the manufacturing process of metal parts. However, this method is also highly sensitive to vibrations that occur during product transportation in the manufacturing process, and vibration signals can interfere with the detection of minute flaw signals. Methods that employ uniform eddy currents[1] or self-differential probes[2], as well as methods that necessitate signal processing, such as multi-frequency methods [3] and frequency filters, have been proposed to attenuate signals other than flaw signals. The authors proposed an electromagnetically passive method that employs dual induction, which simultaneously utilizes self-induction and mutual induction, to suppress solely vibration signals without attenuating flaw signals [4]. In this paper, we discuss how to design a dual-guidance probe. Fig. 1 shows a simulation model of a dual induction differential ECT probe. This probe comprises four coils, designated L1 to L4. L2 and L3 are designated as the internal coils, while L1 and L4 are designated as the external coils. The distances between L1 and L2 and between L3 and L4 are always identical. This distance is defined as the coil distance. Since the appropriate coil distance differs depending on the test conditions, there is a need for a cost-saving method to determine the suitable coil distance that does not rely on trial and error through numerical experiments or prototyping. Fig. 2 shows the outcomes of a simulation investigating the relationship between skin depth and optimal coil spacing. It can be observed that the optimal coil spacing is contingent on the skin depth. This indicates that it is suitable to determine the coil spacing based on the skin depth matching to the flaw depth.It was elucidated that the coil spacing of the dual induction probe should be determined from the skin depth, which matches the depth position of the flaw in the object to be detected, rather than considering the excitation frequency and conductivity separately. The results of the measurement experiment will be presented orally.References: [1] Ageng S. Repelianto and Naoya Kasai, Sensors, Vol. 19, No. 2, 397 (2019) [2] B. Wincheski, J. P. Fulton, S. Nath and M. Namkung, Materials Evaluation, Vol. 52, No. 1, pp. 22–26 (1994) [3] Don E. Bray and Roderic K. Stanley, CRC Press, pp. 418-419 (1997) [4] Daigo Kosaka, Yuji Kumakura, and Fumio Kojima, IEEE Transactions on Magnetics, Vol. 59, No. 11, pp. 1-6 (2023)
In comparison to other non-destructive testing methods, eddy current testing (ECT) can detect minute surface defects that occur during the manufacturing process of metal parts. However, this method is also highly sensitive to vibrations that occur during product transportation in the manufacturing process, and vibration signals can interfere with the detection of minute flaw signals. Methods that employ uniform eddy currents[1] or self-differential probes[2], as well as methods that necessitate signal processing, such as multi-frequency methods [3] and frequency filters, have been proposed to attenuate signals other than flaw signals. The authors proposed an electromagnetically passive method that employs dual induction, which simultaneously utilizes self-induction and mutual induction, to suppress solely vibration signals without attenuating flaw signals [4]. In this paper, we discuss how to design a dual-guidance probe. Fig. 1 shows a simulation model of a dual induction differential ECT probe. This probe comprises four coils, designated L1 to L4. L2 and L3 are designated as the internal coils, while L1 and L4 are designated as the external coils. The distances between L1 and L2 and between L3 and L4 are always identical. This distance is defined as the coil distance. Since the appropriate coil distance differs depending on the test conditions, there is a need for a cost-saving method to determine the suitable coil distance that does not rely on trial and error through numerical experiments or prototyping. Fig. 2 shows the outcomes of a simulation investigating the relationship between skin depth and optimal coil spacing. It can be observed that the optimal coil spacing is contingent on the skin depth. This indicates that it is suitable to determine the coil spacing based on the skin depth matching to the flaw depth.It was elucidated that the coil spacing of the dual induction probe should be determined from the skin depth, which matches the depth position of the flaw in the object to be detected, rather than considering the excitation frequency and conductivity separately. The results of the measurement experiment will be presented orally.References: [1] Ageng S. Repelianto and Naoya Kasai, Sensors, Vol. 19, No. 2, 397 (2019) [2] B. Wincheski, J. P. Fulton, S. Nath and M. Namkung, Materials Evaluation, Vol. 52, No. 1, pp. 22–26 (1994) [3] Don E. Bray and Roderic K. Stanley, CRC Press, pp. 418-419 (1997) [4] Daigo Kosaka, Yuji Kumakura, and Fumio Kojima, IEEE Transactions on Magnetics, Vol. 59, No. 11, pp. 1-6 (2023)