1999 Fiscal Year Final Research Report Summary
Development of Genetic Algorithms based System for High-Precision Reconstructions of Three-Dimensional Topographies using Stereo Fractographs
| Project/Area Number |
10555029
|
|---|
| Research Category |
Grant-in-Aid for Scientific Research (B)
|
| Allocation Type | Single-year Grants |
|---|
| Section | 展開研究 |
|---|
| Research Field |
Materials/Mechanics of materials
|
|---|
| Research Institution | KYOTO UNIVERSITY |
|---|
Principal Investigator |
MINOSHIMA Kohji Kyoto University, Graduate School of Eng., Dept. Mech. Eng., Associate Professor, 工学研究科, 助教授 (50174107)
|
|---|
| Co-Investigator(Kenkyū-buntansha) |
TANAKA Kazuto Kyoto University, Graduate School of Eng., Dept. Mech. Eng., Instructor, 工学研究科, 助手 (50303855)
KOMAI Kenjiro Kyoto University, Graduate School of Eng., Dept. Mech. Eng., Professor, 工学研究科, 教授 (70025948)
|
|---|
| Project Period (FY) |
1998 – 1999
|
| Keywords | Fracture Surface / Fractography / Stereography / Three-Dimensional Shape / Genetic Algorithms / Image Processing / Searching the Matching Points / Field-Emission, High-Resolution Scanning Electron Microscope |
|---|
| Research Abstract |
A software is developed which enables reconstruction of the three-dimensional (3-D) shape of fracture surfaces without human assistance. It is based upon computer image processing and pattern recognition techniques by using a stereo-pair of scanning electron micrographs. The processing consists of two subprocesses : searching the matching points between two images and computation of heights using the relative shift of the matching points. By using the previously developed system, some mismatches were inevitable in the search process, in particular, for low-contrast SEM images such as striations, intergranular facets, and so on. In order to improve the accuracy of the search, a Genetic Algorithm (GA) was implemented into the developed system. By using the GA method, the 3-D shapes of a wide variety of fracture surfaces including cleavage failures, intergranular cracking, dimples and fatigue striations, were successfully reconstructed with sufficient accuracy. The searching processes by the GA method and the previously developed two-step algorithm of coarse and close searching were compared. These proved that the GA method has the advantage of accuracy in the searching process and of short-run-time. A detailed 3-D shape, or more than a 120×120 reconstructed point-sized shape, was thus obtained with sufficient accuracy and with a relatively short-run-time. The developed system was also applied to the fatigued fracture surfaces of a stainless steel (SUS316NG) and a low-alloy steel (SGV420), and the relationship between quantitative topographic measures and stress intensity factors and/or crack growth rates was discussed.
|
