Examination on subsurface fatigue crack generation from the viewpoints of dislocation collective motion and strain incompatibility
| Project/Area Number |
16K06769
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| Research Category |
Grant-in-Aid for Scientific Research (C)
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| Allocation Type | Multi-year Fund |
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| Section | 一般 |
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| Research Field |
Structural/Functional materials
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| Research Institution | Yokohama National University |
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Principal Investigator |
UMEZAWA Osamu 横浜国立大学, 大学院工学研究院, 教授 (20343171)
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| Co-Investigator(Renkei-kenkyūsha) |
KOGA norimitsu
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| Project Period (FY) |
2016-04-01 – 2019-03-31
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| Project Status |
Completed (Fiscal Year 2018)
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| Budget Amount *help |
¥4,680,000 (Direct Cost: ¥3,600,000、Indirect Cost: ¥1,080,000)
Fiscal Year 2018: ¥910,000 (Direct Cost: ¥700,000、Indirect Cost: ¥210,000)
Fiscal Year 2017: ¥1,430,000 (Direct Cost: ¥1,100,000、Indirect Cost: ¥330,000)
Fiscal Year 2016: ¥2,340,000 (Direct Cost: ¥1,800,000、Indirect Cost: ¥540,000)
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| Keywords | 高強度合金 / 疲労 / 粒界 / すべり変形 / き裂 / 応力集中 / 信頼性 |
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| Outline of Final Research Achievements |
Subsurface microcrak generation in high-cycle fatigue of α-titanium alloy, austenitic steel and silicon steel was clarified from the viewpoints of heterogeneous deformation and strain incompatibility developed at boundaries. Then a new model of microcrack generation was proposed. Although the boundaries developed strain incompatibility depended on the test materials and test temperature, the localized plastic deformation accompanied with strain incompatibility in the vicinity of boundaries forms a void and microstructural cracking at the leading edge of void. Its microcrack growth on a specific plane reveals a crystallographic facet, and it provides the subsurface crack fatigue failure.
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| Academic Significance and Societal Importance of the Research Achievements |
高サイクル疲労における擬へき開破壊や粒界破壊などの結晶組織を反映した微視割れは、転位堆積による応力集中が直接的に脆性的な微小き裂形成を与えるモデルが提示されてきたが、長年にわたり実験的検証が得られていない状況にあった。本研究成果は、局所的塑性変形集中が微視割れの原因を与えることことを実験的に明らかにし、従来の考えから大きな進展をもたらそうとするものである。延性金属の曲げ疲労における粒界き裂形成や、転動疲労などのより複雑な変形条件下におけるき裂形成についても視野に入れており、疲労き裂発生機構についての統一的・学術的理解を導き、長寿命へ向けた材質制御、結晶塑性モデル計算などへの反映が期待できる。
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Report
(4 results)
Research Products
(35 results)
