Application of ultrasonic nondestructive testing methods to the mechanical properties of sea ice

2022 Fiscal Year Final Research Report

• Project/Area Number: 20K04955
• Research Category: Grant-in-Aid for Scientific Research (C)
• Allocation Type: Multi-year Fund
• Section: 一般
• Review Section: Basic Section 24020:Marine engineering-related
• Research Institution: National Institute of Maritime, Port and Aviation Technology
• Principal Investigator: Matsuzawa Takatoshi 国立研究開発法人海上・港湾・航空技術研究所, その他部局等, 研究員 (00443242)
• Project Period (FY): 2020-04-01 – 2023-03-31
• Keywords: 海氷の機械的性質 / 超音波探傷法 / 海氷構造

Outline of Final Research Achievements

The response of sea ice to ultrasound as a material property was investigated. A method was established for making model ice samples in the laboratory that simulate sea ice with additives. Canti-lever bending tests were conducted to evaluate changes due to salinity, and it was found that flexural strength of model ice could be controlled within a certain range. In parallel, sea ice samples were collected in East Hokkaido, and flexural strength data were obtained in the field. Sound velocity was measured for the model ice samples made in the laboratory, and it was found that the speed of sound was lower for model ice than for pure ice. The time series of sound pressure intensity was also compared, and it was found that, unlike pure ice, model ice contains complex sound reflection effects. These results may be because model ice contains brine as well as sea ice, and we would like to pursue the quantitative relationship regarding brine volume in more detail in the future.

Free Research Field

船舶海洋工学

Academic Significance and Societal Importance of the Research Achievements

氷の超音波応答を見る先行研究はほとんどなく、特に海氷では計測も困難であってデータがない。そこで、海氷の代わりに海氷構造を模擬した模型氷を用いるという点は例がなく、そのデータを取得したことは意義が大きい。製氷を伴う実験では、製氷方法及び環境が氷質に大きく影響する。実験のために氷質を制御可能な環境を構築したことは、今後の類似研究にも応用でき有用である。得られた氷質と音圧データを照らし合わせると、実氷について最低限の計測をすれば非破壊で強度を推定することが可能となる。実氷データは今まで計測が困難で蓄積が極端に少ないが、非破壊手法が実現すればデータ拡充と計測の安全性に寄与するところ大である。