| Project/Area Number |
18K13716
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| Research Category |
Grant-in-Aid for Early-Career Scientists
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| Allocation Type | Multi-year Fund |
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| Review Section |
Basic Section 20010:Mechanics and mechatronics-related
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| Research Institution | The University of Shiga Prefecture |
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Principal Investigator |
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| Project Period (FY) |
2018-04-01 – 2020-03-31
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| Project Status |
Completed (Fiscal Year 2019)
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| Budget Amount *help |
¥4,290,000 (Direct Cost: ¥3,300,000、Indirect Cost: ¥990,000)
Fiscal Year 2019: ¥1,170,000 (Direct Cost: ¥900,000、Indirect Cost: ¥270,000)
Fiscal Year 2018: ¥3,120,000 (Direct Cost: ¥2,400,000、Indirect Cost: ¥720,000)
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| Keywords | 超音波振動 / 自励振動 / 非線形波動変調 / 局所フィードバック制御 / 接触型損傷 / 超音波 / 非線形振動 / 損傷検出 / 自励駆動 / 固有振動 / 非線形 / モニタリング |
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| Outline of Final Research Achievements |
The detection method of contact-type failure based on nonlinear wave modulation can detect and evaluate the contact-type failure by the fluctuation amplitude of the amplitude and the phase of ultrasonic vibrations.In this study, it is focused that the essence of nonlinear wave modulation is the fluctuation of natural frequency caused by the fluctuation of stiffness in the vicinity of failure. Firstly, the self-excitation technique of ultrasonic vibration, which is oscillation at natural frequencies automatically, is developed. Next, it is clarified that oscillation frequencies change by following the fluctuation of natural frequencies caused by nonlinear wave modulation. Lastly, the evaluation of development of the contact-type failure, which is independent of change of viscous damping of structures,is realized using the fluctuation amplitude of the oscillation frequencies.
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| Academic Significance and Societal Importance of the Research Achievements |
疲労き裂や複合材料のはく離などの損傷は、損傷界面が接触しており検出困難な接触型損傷を有する。接触型損傷の大きさを正確に評価することは、構造物の耐久度,余寿命を推定する上で重要である。非線形波動変調に基づく損傷検出法は、微小な接触型損傷も精度よく検出できる。一方で、これらの損傷は損傷の進展に伴い構造物の粘性減衰を変化させてしまう。非線形波動変調により超音波振動の振幅や位相に生じる変動成分は粘性減衰の変化に依存する。本研究では非線形波動変調の本質である固有振動数変動に着目することで、粘性減衰に依存せず損傷を評価できる手法を開発した。
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