Benefits of GMR sensors for high spatial resolution NDT applications

Pelkner, Matthias; Stegemann, Robert; Sonntag, Nadja; Pohl, Rainer; Kreutzbruck, Marc

doi:10.1063/1.5031535

Cited by 7 publications

(1 citation statement)

References 25 publications

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“…The most recent research presents the magneto-resistive sensors in ECT techniques due to their linear response which makes them suitable for detecting low-amplitude electromagnetic field when a low frequency is applied. 2,3 They have been used successfully for detecting subsurface cracks under riveted structures, [4][5][6] and for concurrent investigation of materials at various depths. This is the enormous feature of utilizing sensors relative to coils.…”

Section: Introductionmentioning

confidence: 99%

Hybrid GMR/IR probe to reduce the effects of lift-off

Faraj

Samsuri

Abdalla

et al. 2019

Measurement and Control

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Eddy current testing technique is being utilized in engineering, such as in nuclear steam pipe, aircraft and gas/oil pipeline, due to its sensitivity to small cracks and subsurface defects, immediate results, environmental friendliness, and use in examining complex sizes and shapes of substances. However, the lift-off noise due to irregular inspected materials surface, varying coating thicknesses, or movement of transducers extremely limits the implementation of eddy current testing in a non-disastrous testing which impacts the measure of defect depth on the conductive material. In this paper, a study on hybrid giant magneto-resistance/infrared probe is proposed to minimize the influence of lift-off for detecting the depth defect. The giant magneto-resistance reads the magnetic field which reflects any defect inside the pipeline, and infrared sensors read the movement of each giant magneto-resistance inside the pipeline. The error compensation technique depends on Mamdani fuzzy which examines the interaction that exists between the peak value of giant magneto-resistance and the infrared sensor signal. The eddy current testing inspection system includes details of the giant magneto-resistance–eddy current probe design and instrumentation of the error compensation technique. The measurement method is based on alternating current supply with 30 kHz frequency to ensure that the crack signals are clearly displayed. The proposed method is verified experimentally, and the result shows that the impact of lift-off noise is highly reduced in the eddy current testing technique and enhances the sensor accuracy. The depth defect error caused by 1 mm lift-off is reduced to 7.20%.

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Section: Introductionmentioning

confidence: 99%

Hybrid GMR/IR probe to reduce the effects of lift-off

Faraj

Samsuri

Abdalla

et al. 2019

Measurement and Control

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Giant Magnetoresistance (GMR) Materials and Devices for Biomedical and Industrial Applications

Saha

et al. 2022

Spintronics

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Subsurface and Bulk Residual Stress Analysis of S235JRC + C Steel TIG Weld by Diffraction and Magnetic Stray Field Measurements

Mishurova

Stegemann²,

Lyamkin

et al. 2022

Exp Mech

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Background Due to physical coupling between mechanical stress and magnetization in ferromagnetic materials, it is assumed in the literature that the distribution of the magnetic stray field corresponds to the internal (residual) stress of the specimen. The correlation is, however, not trivial, since the magnetic stray field is also influenced by the microstructure and the geometry of component. The understanding of the correlation between residual stress and magnetic stray field could help to evaluate the integrity of welded components. Objective This study aims at understanding the possible correlation of subsurface and bulk residual stress with magnetic stray field in a low carbon steel weld. Methods The residual stress was determined by synchrotron X-ray diffraction (SXRD, subsurface region) and by neutron diffraction (ND, bulk region). SXRD possesses a higher spatial resolution than ND. Magnetic stray fields were mapped by utilizing high-spatial-resolution giant magneto resistance (GMR) sensors. Results The subsurface residual stress overall correlates better with the magnetic stray field distribution than the bulk stress. This correlation is especially visible in the regions outside the heat affected zone, where the influence of the microstructural features is less pronounced but steep residual stress gradients are present. Conclusions It was demonstrated that the localized stray field sources without any obvious microstructural variations are associated with steep stress gradients. The good correlation between subsurface residual stress and magnetic signal indicates that the source of the magnetic stray fields is to be found in the range of the penetration depth of the SXRD measurements.

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Benefits of GMR sensors for high spatial resolution NDT applications

Cited by 7 publications

References 25 publications

Hybrid GMR/IR probe to reduce the effects of lift-off

Hybrid GMR/IR probe to reduce the effects of lift-off

Giant Magnetoresistance (GMR) Materials and Devices for Biomedical and Industrial Applications

Subsurface and Bulk Residual Stress Analysis of S235JRC + C Steel TIG Weld by Diffraction and Magnetic Stray Field Measurements

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