Study on improvement of defect detection algorithm for non-contact acoustic inspection

2017 Fiscal Year Final Research Report

• Project/Area Number: 15K06195
• Research Category: Grant-in-Aid for Scientific Research (C)
• Allocation Type: Multi-year Fund
• Section: 一般
• Research Field: Structural engineering/Earthquake engineering/Maintenance management engineering
• Research Institution: Toin University of Yokohama
• Principal Investigator: Kazuko Sugimoto 桐蔭横浜大学, 工学(系)研究科(研究院), 研究員(移行) (60642171)
• Co-Investigator(Kenkyū-buntansha): 杉本 恒美 桐蔭横浜大学, 工学(系)研究科(研究院), 教授(移行) (80257427)
• Research Collaborator: UTAGAWA NORIYUKI 佐藤工業㈱, 技術研究所 ; KURODA CHITOSE 佐藤工業㈱, 技術研究所 ; UECHI ITSUKI 桐蔭横浜大学, 大学院工学研究科, 研究員 ; KOSUGE NOBUAKI 桐蔭横浜大学, 大学院工学研究科, 大学院生
• Project Period (FY): 2015-04-01 – 2018-03-31
• Keywords: 非接触非破壊検査法 / コンクリート内部欠陥検出 / 振動エネルギー比 / スペクトルエントロピー / 欠陥検出アルゴリズム / コンクリート健全部評価 / LRAD / レーザドップラ振動計

Outline of Final Research Achievements

In order to detect an internal defect (a crack, a peeling, a cavity) of concrete structures, noncontact non-destructive inspection method from a long distance was studied. Using airborne sound waves and a laser Doppler vibrometer, internal defects up to 10 cm deep from the concrete surface can be measured from a distance of 30 m at present. In this research, we proposed a defect detection algorithm using acoustic features such as vibration energy ratio and spectral entropy. It was verified with a concrete wall specimen containing several circular cavity or peeling defects, and good results were obtained. Furthermore, in order to cope with actual concrete structures, the statistical evaluation of a healthy part of concrete was carried out by healthy-part extraction algorithm using two acoustic feature quantities. Then, the effect to detect internal defects was increased.

Free Research Field

音響工学，医用工学