2023 Fiscal Year Final Research Report
Study on defect detection by spatial spectral entropy (SSE) and healthy part evaluation for noncontact acoustic inspection
| Project/Area Number |
19K04414
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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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| Review Section |
Basic Section 21030:Measurement engineering-related
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| Research Institution | Toin University of Yokohama |
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Principal Investigator |
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| Co-Investigator(Kenkyū-buntansha) |
杉本 恒美 桐蔭横浜大学, 工学研究科, 教授 (80257427)
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| Project Period (FY) |
2019-04-01 – 2024-03-31
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| Keywords | 非接触音響探査法 / 非破壊検査 / Spatial Spectral Entropy / 空間スペクトルエントロピー / SSE / SSE解析 / 共振周波数 / レーザドップラ振動計 |
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| Outline of Final Research Achievements |
The non-contact acoustic inspection method is a technology that performs non-destructive inspection without contact and remotely to detect and visualize internal defects in composite materials, especially concrete. In the experimental method, the object is forced to vibrated with airborne sound waves in the audible range, and a scanning laser Doppler vibrometer is used to measure the two-dimensional vibration velocity distribution on the target plane. As a data analysis method, 'Spatial Spectral Entropy (SSE)' is proposed, which detects the resonance frequency due to the internal defect on the measured plane and the resonance frequency due to a laser Doppler vibrometer, and can distinguish between the two. By narrowing down the visualization frequency to the resonance frequency band detected by the SSE analysis and visualizing it, various noises can be reduced and an acoustic internal defect image that can distinguish between the defective part and a healthy part can be obtained.
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| Free Research Field |
複合領域(応用物理，波動計測，音響，非破壊検査)
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| Academic Significance and Societal Importance of the Research Achievements |
Shannon's entropyの原理に基づくSSEを用いれば，面的波動計測データから，周波数空間上の物理量分布を見分けられ，学術的意義が大きい。音響探査では，対象面の内部欠陥の共振周波数およびレーザドップラ振動計のヘッドの共振周波数の検出ができ，両者を識別できる。
近年、橋梁やトンネル等のコンクリート構造物の劣化が社会問題となり、その点検・補修・更新が重要である。本手法では，遠隔から内部欠陥の検出が可能で，高所足場の設置が必要ない上，熟練者による経験と判断に依存する叩き点検と異なり，定量的データの取得・解析ができる。少子化に伴う叩き点検の後継者不足の解決にも繋がるため，社会的意義が大きい。
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