2022 Fiscal Year Annual Research Report
渦電流磁気指紋法を用いた電磁鋼板における残留応力と損失の評価
| Project/Area Number |
22J13483
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| Allocation Type | Single-year Grants |
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| Research Institution | Tohoku University |
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| Research Fellow |
張 書睿 東北大学, 流体科学研究所, 特別研究員(DC2)
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| Project Period (FY) |
2022-04-22 – 2024-03-31
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| Keywords | non-destructive testing / elastic stress / plastic strain / hysteresis loss / iron loss |
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| Outline of Annual Research Achievements |
The investigation focused on exploring the influence of elastic stress on magnetic behaviors, particularly within micro-magnetic structures. A variety of measurement techniques were employed, including hysteresis curve analysis, Magnetic Barkhausen Noise (MBN), and Magnetic Incremental Permeability (MIP) signals, allowing for comprehensive analyses. Through comparative studies, specific indicators were identified that demonstrated correlations with elastic stress, providing insights into the evolution of magnetic microstructure. Notably, both MBN and MIP exhibited sensitivity to elastic stress, revealing microstructural changes characterized by heightened 180° domain walls and increased pinning site strength.
Furthermore, the research also evaluated indicators sensitive to plastic strains across several electrical steel specimens. Through comparative analysis, indicators showcasing linear relationships with plastic strain or its square root were uncovered. Remarkably, indicators such as MIP hysteresis area, maximal MIP value, and MBN coercivity displayed significant linear correlations with plastic strain, further confirmed by their predictive capability for hysteresis loss.
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| Current Status of Research Progress |
Current Status of Research Progress
2: Research has progressed on the whole more than it was originally planned.
Reason
The research topic aims to investigate the magnetic behaviors of electrical steel under mechanical deformation, and to explain the changes in magnetic properties through the evolution of micro-magnetic structures. Additionally, the study seeks to explore sensitive indicators applicable to non-destructive testing environments based on magnetic behaviors. In the completed work, the focus was on studying the influence of magnetic behaviors by elastic stress, with particular attention to micro-magnetic structures. Various techniques were used for measurement, including hysteresis curve analysis, Magnetic Barkhausen Noise (MBN), and Magnetic Incremental Permeability (MIP) signals, to conduct comparative analysis. Specific indicators were identified to establish correlations with elastic stress, elucidating the evolution of magnetic microstructure.
Here are some self-evaluation on this work:
1.Successfully researched the magnetic behaviors of electrical steel in both plastic and elastic stages, providing a comprehensive perspective on the material's magnetic response under different stress conditions.
2. Made full use of simulation techniques to simulate and analyze the magnetic behaviors of materials under different stress conditions, enriching the research methods and providing deeper support for the interpretation of research results.
3. It should be pointed out that the material thickness (0.35mm) is the practical issues encountered in applying compressive stress, making the stress type is still limited in tension.
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| Strategy for Future Research Activity |
The next steps for advancing this research topic should address several key points:
1. Future research should utilize magneto-optical effects to directly observe dynamic changes in magnetic domains. While current understanding relies on simulations and theory to interpret micro-magnetic structure changes, real-time observation using magneto-optical techniques will provide valuable insights into the underlying mechanisms affecting electromagnetic properties. But this is a big challenge due to the limitation of technology.
2. A hypothesis has been proposed regarding the increase in pinning site strength as a mechanism for how elastic stress affects the micro-magnetic structure. However, this hypothesis is based solely on experimental and model results. To validate this hypothesis, it would be beneficial to employ a multi-scale model that incorporates energy considerations. This approach can provide a more robust validation of the proposed mechanism.
3. Beyond the elastic stress and plastic strain ranges investigated in this study, the low plastic strain stage near the yield point holds both research significance and challenges. Exploring this stage further could provide valuable insights and directions for future investigations. It is important to extend the research focus to include this aspect and explore its implications on magnetic behaviors comprehensively.
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