Development of Mathematical Model-Based Methods for Evaluating Defects Independent of Electromagnetic Properties or Initial States

2023 Fiscal Year Final Research Report

• Project/Area Number: 20K05000
• Research Category: Grant-in-Aid for Scientific Research (C)
• Allocation Type: Multi-year Fund
• Section: 一般
• Review Section: Basic Section 25020:Safety engineering-related
• Research Institution: Tohoku University
• Principal Investigator: Cheng Weiying 東北大学, 工学研究科, 講師 (40739661)
• Project Period (FY): 2020-04-01 – 2024-03-31
• Keywords: 非破壊検査・評価 / 電磁気計測 / 数理モデル / 電磁気特性 / 損傷評価 / 材料劣化 / 欠陥 / 減肉

Outline of Final Research Achievements

Electromagnetic properties, or their initial states, are crucial for Electromagnetic non-destructive testing and evaluation (EMNDT&E), yet challenging to obtain. Assessing dimension of defects/specimens without prior knowledge of their electromagnetic properties, or characterizing degradations without reference to the virgin state, are vital.
We constructed a mathematical model-based method to valuate wall thinning or layer thickness independently of conductivity. We also devised a method to evaluate the depth of an ideal crack with zero conductivity, independent of the host material’s conductivity. Furthermore, we devised a method to evaluate the depth of a crack with non-zero crack conductivity, without knowledge of the conductivities of the host specimen and inside the crack. In addition, we developed a method to measure conductivity with high sensitivity, thus enables characterizing degradation by correlating changes between electromagnetic properties with mechanical properties.

Free Research Field

電磁気非破壊検査・評価

Academic Significance and Societal Importance of the Research Achievements

電磁気非破壊検査の測定信号は検査対象の寸法と電磁気特性によって変わるため、電磁気特性の把握は寸法評価の前提であるが、被検体の電磁気特性の把握は困難である。また、対象毎に合わせたマスターカーブの作成は現実ではない。本研究では、数理モデルに基づいて、電磁気特性に左右されない損傷評価法を構築できた。よって、一本のマスターカーブを用いて、多様な材質に発生した多様な形態の損傷を評価可能になった。また、共振周波数による導電率測定は高感度であり、材料の劣化評価において感度が向上させた。
これにより、構造物の損傷をより効率且つ高感度に検査・評価可能になった。