Development of multifunctional bolt-type device using magnetostrictive fiber composites

2023 Fiscal Year Final Research Report

• Project/Area Number: 21K03767
• Research Category: Grant-in-Aid for Scientific Research (C)
• Allocation Type: Multi-year Fund
• Section: 一般
• Review Section: Basic Section 18010:Mechanics of materials and materials-related
• Research Institution: Ibaraki University
• Principal Investigator: Mori Kotaro 茨城大学, 理工学研究科(工学野), 講師 (40712740)
• Co-Investigator(Kenkyū-buntansha): 成田 史生 東北大学, 環境科学研究科, 教授 (10312604)
• Project Period (FY): 2021-04-01 – 2024-03-31
• Keywords: 磁歪材料 / センサ特性 / 締結体

Outline of Final Research Achievements

The purpose of this research is to design and develop bolt-type devices made of magnetostrictive composites with a force-sensing function, and to elucidate its sensing and fastening characteristics. The following findings were obtained from this project: 1) We discovered that in bolts made of magnetostrictive composites, the sensing characteristics are improved by applying a preload (tensile and/or torsional stresses) to the magnetostrictive fiber or a magnetic field during fabrication, and that further improvements in characteristics are possible by combining these. We also discovered that the sensing characteristics are improved by an external magnetic field during fastening, and that optimal conditions exist in combination with the conditions during fabrication. 2) We confirmed that the use of a magnetostrictive washer makes it possible to evaluate the axial force inside a normal bolt without contact, using magnetization changes of washer.

Free Research Field

知的材料を用いたデバイス設計・特性評価

Academic Significance and Societal Importance of the Research Achievements

本研究は，軽量，高強度かつ力に対する感知機能を有する磁歪複合材料製ネジの作製を行い，感知・締結特性を理論および実験の両面から評価し，特性向上を目指したものである．磁歪複合材料製ネジは，磁束密度変化と軸力が対応しており，作製条件や外部の磁場により感知特性が大きく変化することがわかった．また，磁歪材料製ワッシャーでもネジの軸力の評価が可能であることが確認できた．以上より，磁歪材料を用いることにより，非接触かつ簡便にネジ内部の軸力評価が可能で，環境に合わせて作製することが可能であることが示された．また，本研究で得られた知見は，IoTや構造ヘルスモニタリングを実施する上で大いに有用となる．