Multi-frequency ECT with AMR sensor

He, Danqing; Shiwa, Mitsuharu; Jia, Jinfen; Takatsubo, J.; Moriya, Shinichi

doi:10.1016/j.ndteint.2011.04.004

Cited by 26 publications

(9 citation statements)

References 5 publications

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“…On the other hand, it has been reported that ECT enables us to obtain much information simultaneously using multifrequency data. (11)(12)(13) In our future work, we will determine whether the harmonic signals generated by using the square excitation wave are applicable to obtaining much information simultaneously. In this study, we chose a small excitation current for the experiment only to determine whether a square-wave inverter is applicable or not.…”

Section: Discussionmentioning

confidence: 99%

Eddy Current Testing Using Square-wave Inverter for Thickness Inspection of Steel Plate

Sasayama

Enpuku

2019

Sensors and Materials

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Eddy current testing (ECT) usually employs a sinusoidal current that flows through an excitation coil. If a square wave instead of a sinusoidal wave is used for excitation, i.e., a square-wave inverter instead of linear amplifiers is used for an ECT system, a handheld ECT system can be developed and the cost can be reduced. In this study, we developed a lowfrequency ECT (LF-ECT) system with a square-wave inverter to determine whether an inverter is applicable to estimating the thickness of a thick steel plate in the range from 6 to 19 mm. The developed ECT system has a differential excitation coil and a pickup coil, and these coils are arranged on the steel plate. A square-wave voltage is applied to the excitation coil, and the voltage of the pickup coil is measured. Subsequently, the mutual equivalent resistance and inductance are calculated. Results indicate that the fundamental component of the resistance increases with the thickness when the frequency is approximately 4 Hz. Furthermore, we determined whether the harmonic signals generated by the inverter are also useful. Results indicate that the harmonic components of the resistance also tend to increase with a sufficiently small increase in thickness, i.e., ≤12 mm. This implies that surface and back-surface defects can be simultaneously obtained.

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Section: Discussionmentioning

confidence: 99%

Eddy Current Testing Using Square-wave Inverter for Thickness Inspection of Steel Plate

Sasayama

Enpuku

2019

Sensors and Materials

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“…For normal ECT equipment, an inductive coil is used, and mainly surface defects are detected. To detect a deep defect, magnetic sensors with high sensitivity at low frequency are used [23][24][25]. The ECT system using the FeCoSiB amorphous magnetic sensor was developed [26].…”

Section: Eddy Current Testing Using the Fecosib Amorphous Magnetic Sementioning

confidence: 99%

PT-Level High-Sensitivity Magnetic Sensor with Amorphous Wire

2019

Sensors

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A picotesla (PT) level high-sensitivity magnetic sensor with amorphous wire was developed. The magnetic sensor was composed of a (Fe0.06Co0.94)72.5Si2.5B15 (FeCoSiB) amorphous wire with a coil wound around it. The amorphous wire had a diameter of 0.1 mm and a length of 5 mm. The coil was 30 turns. There was no electrical connection with the amorphous wire. The sensor was biased by an alternating current (AC) of about 1 MHz and a direct current (DC). To increase the sensitivity, a resonant circuit was used, and the signal amplitude of the magnetic sensor was increased 10 times from 10 mV/Gauss to about 100 mV/Gauss. The magnetic field resolution was improved 5 times from 30 pT/√Hz to 6 pT/√Hz. An eddy current testing system with a magnetic sensor was developed, and the artificial defects in an aluminum plate were evaluated.

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“…We developed an ECT system using the AMR sensor and we successfully detected the artificial defects in plate-type samples [21,22] and chamber-type samples [23], in which grooves and artificial defects were made to simulate the wall of the combustion chamber of a liquid fuel rocket. All experiments were done in an environment without shielding.…”

Section: Application To Ndementioning

confidence: 99%

AMR Sensor and its Application on Nondestructive Evaluation

He¹

2017

Magnetic Sensors - Development Trends and Applications

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To improve the performance of anisotropic magnetoresistance (AMR) sensor, a low-noise driving circuit for the AMR sensor was developed and the magnetic field noise spectral densities of 12 pT/root(Hz) at 1 kHz and 20 pT/root(Hz) at 100 Hz were achieved. The driving circuit could operate in amplifier mode or feedback mode. For the driving circuit with feedback, the distortion of the system was reduced and the AMR sensor was suitable for the applications in the environment without shielding. The Set/Reset method was used to reduce the low frequency noise of the AMR sensor. Due to the low noise of AMR sensor, the eddy current testing (ECT) system with the AMR sensor had the advantage of detecting deep and small defects in metal structures. The dual frequency ECT system was developed to reduce the influence of lift-off variance. Using the ECT system with the AMR sensor, we successfully detected the small defects in the combustion chamber of liquid rocket.

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Multi-frequency ECT with AMR sensor

Cited by 26 publications

References 5 publications

Eddy Current Testing Using Square-wave Inverter for Thickness Inspection of Steel Plate

Eddy Current Testing Using Square-wave Inverter for Thickness Inspection of Steel Plate

PT-Level High-Sensitivity Magnetic Sensor with Amorphous Wire

AMR Sensor and its Application on Nondestructive Evaluation

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