| Project/Area Number |
10450042
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| Research Category |
Grant-in-Aid for Scientific Research (B)
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| Allocation Type | Single-year Grants |
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| Section | 一般 |
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| Research Field |
Materials/Mechanics of materials
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| Research Institution | TOHOKU UNIVERSITY |
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Principal Investigator |
SAKA Masumi Graduate School of Engineering, Tohoku University, Professor, 大学院・工学研究科, 教授 (20158918)
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| Co-Investigator(Kenkyū-buntansha) |
KAMIYA Shoji Graduate School of Engineering, Tohoku University, Associate Professor, 大学院・工学研究科, 助教授 (00204628)
SOYAMA Hitoshi Graduate School of Engineering, Tohoku University, Associate Professor, 大学院・工学研究科, 助教授 (90211995)
MIHARA Tsuyoshi Graduate School of Engineering, Tohoku University, Associate Professor, 大学院・工学研究科, 助教授 (20174112)
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| Project Period (FY) |
1998 – 1999
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| Project Status |
Completed (Fiscal Year 1999)
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| Budget Amount *help |
¥7,500,000 (Direct Cost: ¥7,500,000)
Fiscal Year 1999: ¥3,000,000 (Direct Cost: ¥3,000,000)
Fiscal Year 1998: ¥4,500,000 (Direct Cost: ¥4,500,000)
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| Keywords | Nondestructive Testing / Ultrasonics / Crack / Crack Closure / Ultrasonic Angle Beam Technique / Small Angle of Incidence / Inverse Problem / Theoretical Model / 超音波 / 斜角探傷 |
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| Research Abstract |
The main results obtained are as follows :
1. Clarification of mechanism to enhance the sensitivity of ultrasonic inspection of closed cracks using the ultrasonic angle beam technique
A new evaluation approach, namely the optimum incidence method, has been developed, which provides the way to deal with sensitivity to the smaller cracks, specially the closely ones. It has been verified experimentally by using both fully open and tightly closed 2-D cracks that the evaluation sensitivity can be enhanced significantly when the beam is directed with a small angle of incidence, θィイD2iィエD2 【similar or equal】 2 deg., the response of which is characterized by the nearly antisymmetric variation in amplitude of the back-wall echo signal around the position of the crack.
2. Establishment of theoretical modeling of ultrasonic angle beam response for the evaluation of small closed cracks
For 2-D fatigue cracks having depth of 0.5〜5.0 mm, we have developed method for sizing their depths together with the information of crack closure, by solving an inverse problem on a personal computer. The evaluation method has been extended for plates having different thickness and also for different materials, where it has been found that the evaluation sensitivity is enhanced significantly for the case of thinner plates.
3. Extension of the evaluation method to small 3-D closed cracks
The evaluation method developed above has well been extended to small 3-D closed cracks.
4. Verification of the method by using small closed 3-D surface cracks
We have verified that the method can be successfully applied for the evaluation of depths of small 3-D closed cracks together with the information of their crack closure.
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