Evaluation of cure distribution of FRP plates in the thickness direction using quasi-surface waves

2020 Fiscal Year Final Research Report

• Project/Area Number: 18K03861
• Research Category: Grant-in-Aid for Scientific Research (C)
• Allocation Type: Multi-year Fund
• Section: 一般
• Review Section: Basic Section 18010:Mechanics of materials and materials-related
• Research Institution: Osaka Sangyo University (2020); Kobe City College of Technology (2018-2019)
• Principal Investigator: Wada Akihiro 大阪産業大学, 工学部, 教授 (60321460)
• Project Period (FY): 2018-04-01 – 2021-03-31
• Keywords: FRP / 硬化度分布 / 超音波 / 擬似表面波 / 非破壊検査 / FDTD

Outline of Final Research Achievements

In this study, non-destructive evaluation method for FRP plates with cure distribution in the thickness direction was investigated by studying the propagation characteristic of "quasi-surface waves". At first, FRP plates with cure distribution in the thickness direction were molded using the special designed molding equipment. Then, the existence of "quasi-surface wave", which localize and propagate near the cured surface is confirmed experimentally, and the effect of cure distribution on the propagation characteristics of "quasi-surface waves" are investigated. Furthermore, in order to reproduce the experimental results, the FDTD method, which is a time-domain finite difference analysis, is extended to apply to highly attenuated materials such as uncured FRP plates. It is found that the evaluation of the frequency characteristics and the attenuation of "quasi-surface waves" is effective in evaluating the cured layer thickness.

Free Research Field

材料力学および機械材料関連

Academic Significance and Societal Importance of the Research Achievements

超音波測定法は，材料物性の非破壊評価法として多用されている．金属材料では比較的高周波数の超音波を用いて，表面波による試料厚さ方向の物性分布評価が可能である．一方，FRPのような高減衰材料では低周波数の波しか使用できないため，板厚が小さい場合は純粋な表面波の励起は難しい．本研究では，片面未硬化FRP板の硬化側表面の近傍に局在化して伝播する「擬似表面波」に着目し，その伝播特性を実測およびシミュレーションにより調査した．このような「擬似表面波」に関する研究例は他に見当たらず，本研究成果の学術的意義は大きい．また，本研究成果は，近年社会問題化しているインフラ構造物の老朽化対策に寄与するところが大きい．