Three-dimensional nonlinear ultrasonic imaging method of closed cracks by local cooling

2014 Fiscal Year Final Research Report

• Project/Area Number: 24686081
• Research Category: Grant-in-Aid for Young Scientists (A)
• Allocation Type: Partial Multi-year Fund
• Research Field: Material processing/treatments
• Research Institution: Tohoku University
• Principal Investigator: OHARA Yoshikazu 東北大学, 工学(系)研究科(研究院), 助教 (90520875)
• Project Period (FY): 2012-04-01 – 2015-03-31
• Keywords: 非破壊検査 / 非線形超音波 / 閉じたき裂 / 局所冷却 / フェーズドアレイ / 熱応力

Outline of Final Research Achievements

As a method of accurately measuring closed cracks, nonlinear ultrasonic imaging method was developed by combining the phased array and local cooling. First, we succeeded in significantly enhancing the closed-crack opening ability by global preheating and local cooling (GPLC). As the measurement system, we designed and made transducer and phased array apparatus. By applying it to closed cracks in aluminum alloy and stainless steel specimens, which are widely used in infrastructure, we demonstrated that GPLC is very useful in measuring closed cracks. Furthermore, by formulating one-dimensional heat-transfer and thermal stress analyses, we proposed a crack closure stress estimation method and demonstrated it in closed crack specimens.

Free Research Field

非破壊評価