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2,077 results on '"Graduate School of Engineering, Tohoku University"'

1. Effect of Nd-Rich Phase on c-Axis Orientation of Nd-Fe-B Melt-Spun Magnet and its Domain Structure

Author

Department of Applied Science for Integrated System Engineering, Graduate School of Engineering, Kyushu Institute of Technology, Department of Applied Physics, Graduate School of Engineering, Tohoku University, Energy Electronics Laboratory, Sojo University, Takezawa, M., Aiba, K., Yasuda, H., Morimoto, Y., Hidaka, T., Yamasaki, J., Kato, H., Yagi, M., Department of Applied Science for Integrated System Engineering, Graduate School of Engineering, Kyushu Institute of Technology, Department of Applied Physics, Graduate School of Engineering, Tohoku University, Energy Electronics Laboratory, Sojo University, Takezawa, M., Aiba, K., Yasuda, H., Morimoto, Y., Hidaka, T., Yamasaki, J., Kato, H., and Yagi, M.

Abstract

type:Journal Article, X-ray diffraction and domain observation were performed to evaluate an effect of Nd-rich phase on the c-axis orientation of the Nd–Fe–B melt-spun ribbon. It was found that adequate addition of Nd-rich phase promotes the c-axis orientation of the Nd–Fe–B ribbon. The (Nd2Fe14B1)95(Nd-rich phase)5 ribbon has c-axis orientation in the entire body from bottom to top when melt-spun at wheel speed of 10.0 m/s.

Published
2017

25. Probabilistic analysis of electromagnetic acoustic resonance signals for the detection of pipe wall thinning

Author

Noritaka Yusa, Tetsuya Uchimoto, Makoto Moroi, Daiki Iwata, Toshiyuki Takagi, Haicheng Song, Graduate School of Engineering, Tohoku University, Institute of Fluid Sciences [Sendai] (IFS), Tohoku University [Sendai], ELyTMaX, École Centrale de Lyon (ECL), Université de Lyon-Université de Lyon-Institut National des Sciences Appliquées de Lyon (INSA Lyon), and Université de Lyon-Institut National des Sciences Appliquées (INSA)-Institut National des Sciences Appliquées (INSA)-Tohoku University [Sendai]-Centre National de la Recherche Scientifique (CNRS)

Subjects
010302 applied physics, Physics, false positive, Wall thinning, electromagnetic acoustic transducer, Mechanical Engineering, Acoustics, electromagnetic non-destructive testing, General Physics and Astronomy, pipe inspection, 01 natural sciences, Statistical power, [SPI.ELEC]Engineering Sciences [physics]/Electromagnetism, Mechanics of Materials, 0103 physical sciences, General Materials Science, Probabilistic analysis of algorithms, 010301 acoustics, Electromagnetic acoustic transducer, probability of detection, Acoustic resonance
Abstract

International audience; This study proposes a probability of detection (POD) model for the probabilistic analysis of the detectability of electromagnetic acoustic resonance (EMAR) method for the detection and evaluation of pipe wall thinning. Forty-one carbon steel plate samples with an artificially corroded groove were prepared to simulate pipe wall thinning caused by flow-assisted corrosion. Experiments were performed to gather EMAR signals from the samples, and subsequently the depths of the grooves were evaluated based on the fundamental frequency of the measured signals. The results of the experiments showed that the error in evaluating the depth of a groove tended to increase with the depth. The results also confirmed that the surface roughness of the groove would contribute to the error, and the thickness of a plate without corrosion can be quite accurately evaluated. Analyzing the measured EMAR signals using the proposed POD model, which takes these characteristics into consideration, and a conventional one confirmed that the proposed model can more reasonably evaluate the probability of detection against small wall thinning, as well as the false positive rate.

Published
2019
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30. Effect of Mechanical Surface Treatments on the Surface State and Passive Behavior of 304L Stainless Steel

Author

Hiroshi Abe, Benoît Ter-Ovanessian, Yutaka Watanabe, Kathleen Jaffré, Nicolas Mary, Bernard Normand, Matériaux, ingénierie et science [Villeurbanne] (MATEIS), Université Claude Bernard Lyon 1 (UCBL), Université de Lyon-Université de Lyon-Institut National des Sciences Appliquées de Lyon (INSA Lyon), Université de Lyon-Institut National des Sciences Appliquées (INSA)-Institut National des Sciences Appliquées (INSA)-Centre National de la Recherche Scientifique (CNRS), Graduate School of Engineering, Tohoku University, ELyTMaX, École Centrale de Lyon (ECL), and Université de Lyon-Institut National des Sciences Appliquées (INSA)-Institut National des Sciences Appliquées (INSA)-Tohoku University [Sendai]-Centre National de la Recherche Scientifique (CNRS)

Subjects
lcsh:TN1-997, Materials science, Scanning electron microscope, XRD, 020209 energy, Polishing, 02 engineering and technology, Surface finish, Emery paper, [SPI]Engineering Sciences [physics], 0202 electrical engineering, electronic engineering, information engineering, General Materials Science, Composite material, stainless steel, lcsh:Mining engineering. Metallurgy, Surface states, EIS, Metals and Alloys, surface treatment, 021001 nanoscience & nanotechnology, semiconductive properties, SEM, TEM, Mott-Schottky analysis, Profilometer, Mott–Schottky analysis, passive films, 0210 nano-technology, Layer (electronics), Surface finishing
Abstract

The effect of dry grinding on 304L stainless steel&rsquo, s passive behavior is compared to two other surface finishing (mechanical polishing down to 2400 with SiC emery paper and 1 &micro, m with diamond paste, respectively). The characterization of the surface state was performed using scanning electron microscopy, transmission electron microscopy, 3D optical profilometer, and X-ray diffraction. Results indicate that each surface treatment leads to different surface states. The ground specimens present an ultrafine grain layer and a strong plastic deformation underneath the surface, while an ultrafine grain layer characterizes the subsurface of the polished specimens. Grinding induces high residual compressive stresses and high roughness compared to polishing. The characterization of the passive films was performed by electrochemical impedance spectroscopy and Mott&ndash, Schottky analysis. The study shows that the semiconductor properties and the thickness of the passive films are dependent on the surface state of the 304L stainless steel.

Published
2021
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31. Electromagnetic pulse-induced acoustic testing and the pulsed guided wave propagation in composite/metal adhesive bonding specimens

Author

Naoki Takeshita, Toshiyuki Takagi, Hiroyuki Kosukegawa, Tetsuya Uchimoto, Hongjun Sun, Mitsuo Hashimoto, Institute of Fluid Sciences [Sendai] (IFS), Tohoku University [Sendai], ELyTMaX, École Centrale de Lyon (ECL), Université de Lyon-Université de Lyon-Institut National des Sciences Appliquées de Lyon (INSA Lyon), Université de Lyon-Institut National des Sciences Appliquées (INSA)-Institut National des Sciences Appliquées (INSA)-Tohoku University [Sendai]-Centre National de la Recherche Scientifique (CNRS), and Graduate School of Engineering, Tohoku University

Subjects
Materials science, Adhesive bonding, Composite number, Non-destructive testing, chemistry.chemical_element, Electromagnetic pulse-induced acoustic testing, 02 engineering and technology, 010402 general chemistry, 01 natural sciences, Lamb waves, Multi-material, Aluminium, Nondestructive testing, Guided wave, Composite material, Electromagnetic pulse, Guided wave testing, business.industry, General Engineering, 021001 nanoscience & nanotechnology, 0104 chemical sciences, [SPI.ELEC]Engineering Sciences [physics]/Electromagnetism, chemistry, Ceramics and Composites, Adhesive, 0210 nano-technology, business
Abstract

Materials composed of metals and plastic composites joined through adhesive bonding are being increasingly used. However, debonding of such materials may occur during manufacture or use. Non-destructive testing of adhesive bonding structures is required to evaluate their debonding. Herein, electromagnetic pulse-induced acoustic testing (EPAT) was used to detect debonding at the adhesive joint in plastic composite/metal specimens. EPAT uses a pulsed excitation current to generate guided waves in a specimen to detect debonding without contact, which makes it suitable for testing from the plastic composite side. Simulations were performed to analyze acrylic/aluminum (Al) and carbon fiber-reinforced plastic (CFRP)/Al specimens. The results showed that the Lorentz force in the z direction was the dominant mechanism in the generation of guided waves, and mainly the A0-mode Lamb wave was excited. The simulation and experimental results revealed that for specimens where the mechanical parameters of the plastic composite layer differed greatly from those of the metal, such as the acrylic/Al specimen, debonding could only be detected directly above debonding. Therefore, it is necessary to evaluate the debonding position by scanning the receiver sensor. Conversely, for specimens with reasonably similar mechanical parameters of the plastic composite and metal layers, like the CFRP/Al specimen, the debonding position could be evaluated by scanning the receiver sensor or excitation coil.

Published
2021
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