Study on crack detection and stress intensity factor analysis using a stress stethoscope for countermeasures for aging infrastructure accidents

2022 Fiscal Year Final Research Report

• Project/Area Number: 20K05009
• 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: Suwa University of Science
• Principal Investigator: Shimura Jyo 公立諏訪東京理科大学, 工学部, 准教授 (70390424)
• Co-Investigator(Kenkyū-buntansha): 高田 宗一朗 東京工業高等専門学校, 機械工学科, 准教授 (30835517)
• Project Period (FY): 2020-04-01 – 2023-03-31
• Keywords: 応力拡大係数 / き裂検出 / ひずみ測定 / 応力聴診器 / ひずみゲージ / FEM解析

Outline of Final Research Achievements

In this study, we attempted to analyze the stress intensity factor (KⅡ) for a crack of in-plane shear mode using a strain checker and a tensile shear plate specimen. The strain checker is built in with three friction type strain gauges, and is installed at the measurement point by the magnetic force of the magnet base of the main body. The slits were made in the specimen by wire-cut electric discharge machining, and these were treated as the artificial cracks. The strain at the crack tip is obtained from the strain checker and the specimen, and the KⅡ value can be calculated by applying that value to the analytical equation. Furthermore, the possibility of this analytical method was verified by comparing the case of using the conventional 2-axis orthogonal strain gauge and the extrapolation value using FEM results. As a result, it was found that the analysis accuracy is about 10% except for some cases, while suggesting the possibility of the analysis method using the strain checker.

Free Research Field

材料力学

Academic Significance and Societal Importance of the Research Achievements

応力聴診器を用いた構造部材のき裂検出及びき裂の応力拡大係数解析に関する技術は，低コストかつ簡易性を有する新たな健全性・安全性評価手法として位置付けられ，主として国内の老朽化橋梁構造物の保全・改修に役立てることができる．また，土木分野に限らず，機械及び建築分野でも本技術が適用可能であり将来性・発展性が推察される．
本研究成果は，現状としては実験室レベルであるが，様々な条件下での実験結果を蓄積し知見を深めること，及び次の段階として実地試験に臨むことで，将来的な現場での応用が期待される．これにより，喫緊の問題である老朽化社会インフラの健全性評価技術として，その一翼を担うものと推察される．