| Project/Area Number |
17K06237
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| Research Category |
Grant-in-Aid for Scientific Research (C)
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| Allocation Type | Multi-year Fund |
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| Section | 一般 |
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| Research Field |
Dynamics/Control
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| Research Institution | Keio University |
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Principal Investigator |
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| Project Period (FY) |
2017-04-01 – 2020-03-31
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| Project Status |
Completed (Fiscal Year 2019)
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| Budget Amount *help |
¥4,680,000 (Direct Cost: ¥3,600,000、Indirect Cost: ¥1,080,000)
Fiscal Year 2019: ¥1,430,000 (Direct Cost: ¥1,100,000、Indirect Cost: ¥330,000)
Fiscal Year 2018: ¥1,430,000 (Direct Cost: ¥1,100,000、Indirect Cost: ¥330,000)
Fiscal Year 2017: ¥1,820,000 (Direct Cost: ¥1,400,000、Indirect Cost: ¥420,000)
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| Keywords | 振動学 / 超音波 / 非破壊評価 / ガイド波 / ワイヤロープ |
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| Outline of Final Research Achievements |
In order to establish a non-destructive evaluation method for wire ropes, we focused on nonlinear guided waves including cumulative harmonics and aimed to clarify the dynamic behavior during long-distance propagation. First, considering the effects of nonlinear coupling and damping, the behavior of cumulative harmonics was clarified by theoretical analysis using orthogonality of propagation modes and multiscale method, and verified by numerical analysis and experiments. Next, changes in the vibration mode and propagation velocity were confirmed by theoretical analysis and experiments of mode conversion of guided waves incident on regions of different materials and thickness. Furthermore, for the electromagnetic acoustic transducer EMAT, selective excitation of guided wave input modes was clarified by analysis, and the results were verified by finite element analysis and experiments.
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| Academic Significance and Societal Importance of the Research Achievements |
ワイヤロープの劣化や断線等の同定のために，点計測型の漏洩磁束法や目視検査より，効率的かつ高精度に検出し得る非破壊評価手法の確立が求められている．長大構造物内を遠距離伝播する超音波ガイド波は，全面検査手法として高効率化と高精度化が期待できる．また，初期の疲労き裂や微小なき裂を検出しうる高精度な非線形超音波の利用も期待される．近年，それらの両長所を有した累積的高調波（非線形ガイド波）が注目されているが，その長距離伝播の挙動解明は十分なされていない．本研究での挙動解明により，非線形ガイド波によるワイヤロープの高効率かつ高精度な非破壊評価手法の確立に寄与しうる．
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