2023 Fiscal Year Final Research Report
Defect detection method for orthotropic materials based on the point source constrained PDE
| Project/Area Number |
21K04096
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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 | Saga University |
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Principal Investigator |
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| Project Period (FY) |
2021-04-01 – 2024-03-31
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| Keywords | Lp空間 / 超音波探傷 / 異方性材料 / CFRP / 点波源拘束偏微分方程式 / divergence based imaging / 波面情報処理 |
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| Outline of Final Research Achievements |
Ultrasonic testing (UT) has become the mostly reliable nondestructive testing in the aviation industry with the extensively increasing use of carbon fiber reinforced plastics (CFRP). Nevertheless, CFRP composite material presents inherent difficulties in ultrasonic testing due to its anisotropy of phase velocity. The propagation velocity parallel to the fiber is faster than that propagating in other directions. For this reason, the time-of-flight depends on its propagating direction, and the exact location of the defect cannot be determined by the migration method.
This study formulates the wave propagation on Lp space, and derives the spatio-temporal behavior of the divergent wave front of point-source. And experiments evaluate the reconstructed silhouette of subsurface point-like defect in CFRP plates obtained with using the point source constrained partial differential equation on Lp space.
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| Free Research Field |
計測工学
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| Academic Significance and Societal Importance of the Research Achievements |
現在, 炭素繊維を用いた CFRP積層材は軽量化や強度が必要な構造材に多く使用されているが, 超音波試験に対して本質的な困難さを伴っている. 困難さの一つが音速の異方性である. そのため, 現在用いられている伝播時間にもとづく超音波探傷法では, 傷の位置や形状をうまく捉えることが難しい. 本研究では, この異方性の問題に対して, 波動場をLp距離空間で表現し, その空間内の波動方程式を考え波動伝播問題を考察している. さらに, 本研究が提案する点波源拘束偏微分方程式にもとづく欠損のシルエット像再構成手法は いかなるCFRP積層材においても適用が可能であり, 異方性の問題を解決することができた.
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