Nondestructive evaluation of a bent plate using nonlinear Lamb wave mixing

2020 Fiscal Year Final Research Report

• Project/Area Number: 19K14841
• Research Category: Grant-in-Aid for Early-Career Scientists
• Allocation Type: Multi-year Fund
• Review Section: Basic Section 18010:Mechanics of materials and materials-related
• Research Institution: Kyoto University (2020); Toyohashi University of Technology (2019)
• Principal Investigator: Ishii Yosuke 京都大学, 工学研究科, 助教 (70781706)
• Project Period (FY): 2019-04-01 – 2021-03-31
• Keywords: 超音波非破壊評価 / ラム波 / 平板屈曲部 / モード分解法

Outline of Final Research Achievements

Lamb wave propagation in a bent plate has been studied theoretically, numerically, and experimentally. Using a modal decomposition approach, the scattering of Lamb waves in a bent region has been found to be influenced by the bend angle, bend radius, and frequency. Furthermore, the reciprocal relation between the incident and reflected/transmitted Lamb wave modes has been shown theoretically. These results have been verified by comparing with those of the numerical analysis using a finite element method as well as experiment.
In addition, the nonlinear Lamb wave generation at a boundary between regions with and without a weak material nonlinearity has been investigated theoretically with a perturbation approach.

Free Research Field

機械材料・材料力学

Academic Significance and Societal Importance of the Research Achievements

航空機や自動車をはじめとする様々な産業分野で，薄板を屈曲させた構造が実用されており，このような屈曲部において損傷が発生することが多い．そのため，構造健全性を確保するための超音波非破壊評価が重要である．本研究で着目したラム波の非線形周波数ミキシングは，疲労損傷の早期段階などの従来法では検出が難しい損傷も高感度に評価できる可能性があり，本研究で得られた成果に基づいて本研究をさらに発展させることで，平板屈曲部の新しい超音波非破壊評価法の構築につながると期待される．