| Project/Area Number |
18K03860
|
|---|
| Research Category |
Grant-in-Aid for Scientific Research (C)
|
| Allocation Type | Multi-year Fund |
|---|
| Section | 一般 |
|---|
| Review Section |
Basic Section 18010:Mechanics of materials and materials-related
|
|---|
| Research Institution | Suzuka National College of Technology |
|---|
Principal Investigator |
|
|---|
| Project Period (FY) |
2018-04-01 – 2022-03-31
|
| Project Status |
Completed (Fiscal Year 2021)
|
| Budget Amount *help |
¥4,420,000 (Direct Cost: ¥3,400,000、Indirect Cost: ¥1,020,000)
Fiscal Year 2020: ¥390,000 (Direct Cost: ¥300,000、Indirect Cost: ¥90,000)
Fiscal Year 2019: ¥910,000 (Direct Cost: ¥700,000、Indirect Cost: ¥210,000)
Fiscal Year 2018: ¥3,120,000 (Direct Cost: ¥2,400,000、Indirect Cost: ¥720,000)
|
|---|
| Keywords | 非破壊検査 / 非線形超音波法 / 閉口き裂 / 超音波可視化 / 光弾性法 / 鋭敏色法 / フェーズドアレイ法 / 非線形超音波 / 超音波探傷 / フェーズドアレイ / FDTD法 / 超音波探傷法 / 分調波 / 高調波 / 実験応力ひずみ解析 / 可視化 |
|---|
| Outline of Final Research Achievements |
Cracks existing in mechanical structures are the principal defects that should be detected by non-destructive inspection because they induce sudden brittle fracture and lead directly to a tragic accident.
In this study、 we directly observed the opening and closing behavior of cracks due to the transmission of ultrasonic waves with the aim of improving the inspection accuracy of closed cracks、 which are particularly difficult to detect、 by the non-linear ultrasonic technique. As a result、 it was visually confirmed that the crack opens and reflects the wave when the tensile phase of the longitudinal ultrasonic wave is incident、 and the crack closes and transmits the wave in the compressed phase. Furthermore、 it was found that if an incident wave was focused on the closed crack by using the phased array method、 higher harmonics can be clearly observed as compared with the case of plane wave incident.
|
| Academic Significance and Societal Importance of the Research Achievements |
き裂からの反射エコーを利用する従来の超音波法では、検知が極めて難しい閉口き裂を検出するため、強力な超音波を入射することによって発生する非線形超音波（高調波や分調波）を利用する手法が研究されている。このような非線形超音波の発生要因とされている「き裂の開閉口挙動」を、数値解析などのシミュレーションではなく、実験的に超音波の伝ぱ挙動を可視化して直接観察し、この挙動を視覚的に確かめた。光干渉法によって、nmオーダのき裂開口量(COD)も実験的に測定可能であるため、非線形超音波の発生と CODとの関連性も今後検討が可能である。
|
