| Project/Area Number |
63850024
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| Research Category |
Grant-in-Aid for Developmental Scientific Research
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| Allocation Type | Single-year Grants |
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| Research Field |
材料力学
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| Research Institution | Osaka University |
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Principal Investigator |
OHJI Kiyotsugu Osaka University, Faculty of Engineering, Professor, 工学部, 教授 (20028939)
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| Co-Investigator(Kenkyū-buntansha) |
KUBO Shiro Osaka University, Faculty of Engineering, Associate Professor, 工学部, 助教授 (20107139)
ENDO Tadayoshi Mitsubishi Heavy Industries, Ltd., Takasago Research and Development Center, Ass, 高砂研究所, 主査
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| Project Period (FY) |
1988 – 1989
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| Project Status |
Completed (Fiscal Year 1989)
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| Budget Amount *help |
¥10,400,000 (Direct Cost: ¥10,400,000)
Fiscal Year 1989: ¥1,600,000 (Direct Cost: ¥1,600,000)
Fiscal Year 1988: ¥8,800,000 (Direct Cost: ¥8,800,000)
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| Keywords | Non-Destructive Inspection / Electric Potential Method / Surface Crack / Computed Tomography Method / Inverse Analysis / Fracture Mechanics / Boundary Element Method / Pipe / 裏面き裂 |
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| Research Abstract |
The present investigators proposed the electric potential CT method for estimating locations, shapes and sizes of two- and three-dimensional cracks in conductive bodies from electric potential distributions based on boundary element inversion analysis schemes. In the present study the method was applied for monitoring inner surface cracks in plant pipes. The main results obtained are summarized as follows.
1. A simplified inverse analysis scheme was proposed to identify surface cracks on back-faces by computer processing of the electric potential distribution using a workstation. In this scheme hierarchical method was introduced, in which two-dimensional scanning analyses were combined with three-dimensional inverse analyses. To achieve a high speed computation on the workstation, analytical expressions of electric potential distribution reported by Johnson was used in the two-dimensional scanning analyses, and data base of electric potential distribution on three-dimensional cracked bodies was utilized in the three-dimensional inverse analyses. 2. To automatically determine the crack locations and shapes from electric potential distributions, optimization schemes were incorporated in the crack determination based on the three-dimensional least residual method. 3. Numerical simulations were conducted for determining crack locations and shapes from electric potential distributions. It was shown that the proposed schemes worked well for the determination of cracks. 4. The data base of electric potential for cracked plates can be used for identifying cracks in plates with curvature or pipes, if cracked area was taken as a major variable of the electric potential distribution. 5. The electric potential distributions were measured on surfaces of cracked plates and pipes. The location and shape of cracks were successfully identified from the electric potential distributions by the proposed schemes. 6. These results showed the usefulness of the proposed schemes.
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