1993 Fiscal Year Final Research Report Summary
Development of Three Dimensional Strain Measurement System around Crack Tip by Means of Image Processing
| Project/Area Number |
04555025
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| Research Category |
Grant-in-Aid for Developmental Scientific Research (B)
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| Allocation Type | Single-year Grants |
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| Research Field |
機械材料工学
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| Research Institution | Yamaguchi University |
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Principal Investigator |
HATANAKA Kenji Yamaguchi Univ., Mechanical Engineering, Professor, 工学部, 教授 (60026193)
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| Co-Investigator(Kenkyū-buntansha) |
KOSUGE Takao Japam Electro-Technics CO.Ltd., R&D,ChiefManager, 技術開発部, 部長
OHGI Junji Yamaguchi Univ., Mechanical Engineering, Research Associate, 工学部, 助手 (80223965)
FUJIMITSU Tatsurou Tokuyama College of Technology, Mechanical and Electrical Engineering, Professor, 機械電気工学科, 教授 (70035062)
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| Project Period (FY) |
1992 – 1993
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| Keywords | Image Processing Technique / Grid Method / Localized Strain Measurements / Crack Analysis / High Temperature Creep / Elastic-Plastic Fracture Mechanics / 弾塑性破壊力学 |
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| Research Abstract |
The grid pattern with space-interval of 20-30mum was described around fatigue crack tip in copper and circular hole machined at the center of stainless steel plate specimen. Then variation of localized strain near crack tip during one load cycling and three dimensional high temperature creep strain around circular hole were successfully measured, where the displacement of grids was measured using an optical microscope as a first step.
Subsequently, the image processing technique was introduced to measure the displacement of the grid around the circular hole under high temperature creep loading. The acethylcellulose film replica was taken from the location at which the grid pattern with space-interval of 50mum was described around the circular hole of tensile creep specimen. Then gold-spattering was treated to observe this through scanning electron microscope. The magnification of the dynamic range (DR) was conducted to intensify the contrast of image taken through SEM.Subsequently, the unevenness of brightness was removed by conducting shading correction, and then filter treatment was made.
The two-valued image treatment was conducted at brightness of 254 so that the grid was valued at brightness of zero and the background at 255 in the SEM image. Then the spike noise was fully removed through a rank filter. Such treatments were repeated, and then the clear two-valued image was attained. Thus, we obtained a bright prospect to apply the image processing technique to measurement of localized strain around crack tip and high temperature creep strain.
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