| Project/Area Number |
62460078
|
|---|
| Research Category |
Grant-in-Aid for General Scientific Research (B)
|
| Allocation Type | Single-year Grants |
|---|
| Research Field |
材料力学
|
|---|
| Research Institution | The University of Electro-Communications |
|---|
Principal Investigator |
ICHIKAWA Masahiro The University of Electro-Communications, Department of Mechanical and Control Engineering Professor, 電気通信学部, 教授 (80017334)
|
|---|
| Co-Investigator(Kenkyū-buntansha) |
TAKAMATSU Tohru The University of Electro-Communications, Department of Mechanical and Control E, 電気通信学部, 助手 (00106890)
AKITA Satoshi The University of Electro-Communications, Department of Mechanical and Control E, 電気通信学部, 助教授 (60017390)
|
|---|
| Project Period (FY) |
1987 – 1989
|
| Project Status |
Completed (Fiscal Year 1989)
|
| Budget Amount *help |
¥7,200,000 (Direct Cost: ¥7,200,000)
Fiscal Year 1989: ¥900,000 (Direct Cost: ¥900,000)
Fiscal Year 1988: ¥2,800,000 (Direct Cost: ¥2,800,000)
Fiscal Year 1987: ¥3,500,000 (Direct Cost: ¥3,500,000)
|
|---|
| Keywords | Remaining life evaluation / Creep-fatigue / Short cracks / Statistics of extremes / Image processing / Reliability engineering / 疲労寿命 / 再帰期間 / 信頼性評価 / 高温疲労 |
|---|
| Research Abstract |
This research was conducted aiming at development of a liability-based method for remaining life evaluation. The method makes use of the maximum crack length estimated by means of statistics of extremes and image processing. The research involves construction of a high temperature fatigue testing system (mainly, a control system using a microcomputer and a strain measurement system), execution of creep-fatigue tests of the austenitic stainless steel SUS316L at 650 ﾟC in air, introduction of image processing technique including development of some new algorithms, size measurement of a large number of short fatigue cracks, estimation of the maximum crack length based on statistics of extremes at a constant interval of strain cycles and comparison with the measured value, and development of a reliability-based method for remaining life evaluation. The principal results are summarized as follows.
First, image processing was successfully applied to size measurement of a large number of short fatigue cracks to which statistics of extremes was applied. The time and efforts consumed in measurement could be greatly reduced. It was possible to measure the crack length larger than 30 gm within the relative error of <plus-minus>10
Second, a limitation of estimating the maximum crack length in creep-fatigue was found. That is, it was found that up to occurrence of crack coalescence, the estimated maximum crack length was in agreement with the measured one, whereas after occurrence of coalescence the former deviated from the latter. This is important in remaining life evaluation based on the maximum crack length.
Finally, the new concept of "modified return period" was proposed , and a reliability-based method for remaining life evaluation was developed using this concept. This method enables to predict the remaining life corresponding to a low failure probability (or high reliability).
|
