Development and evaluation with theory of crack

Research Project

Project/Area Number	16K14120
Research Category	Grant-in-Aid for Challenging Exploratory Research
Allocation Type	Multi-year Fund
Research Field	Materials/Mechanics of materials
Research Institution	Kyushu University
Principal Investigator	Hiroshi Noguchi 九州大学, 工学研究院, 教授 (80164680)
Project Period (FY)	2016-04-01 – 2018-03-31
Project Status	Completed (Fiscal Year 2017)
Budget Amount *help	¥2,860,000 (Direct Cost: ¥2,200,000、Indirect Cost: ¥660,000) Fiscal Year 2017: ¥1,560,000 (Direct Cost: ¥1,200,000、Indirect Cost: ¥360,000) Fiscal Year 2016: ¥1,300,000 (Direct Cost: ¥1,000,000、Indirect Cost: ¥300,000)
Keywords	き裂 / 疲労限度 / 停留 / 硬さ / 炭素 / 金属疲労 / 硬度 / 特異点 / 材料評価 / 機械材料・材料力学
Outline of Final Research Achievements	A. The fatigue limit ratio of the stellwas σ w0/ (ultimate tensile strength) =0.65 and σ w0/ lower yield strength = 1.13,when Interstitial Carbon tentent is 0.18%. All fatigue cracks which occurred in the grain boubdary have been stopped in the grain bundary and fatigue fracture was occured by coalescence of the intergranular fatigue crack.The relationship between ΔＫth and interstitial Carbon content was measured. B. I showed analytically that there is correlation in the singular distribution of the strain by the crack and the siglar distribution of the strain by the Vickers impression. The best indenter shape under the two-dimensional plane strain condition was proposed dependent on the work-hardening coefficient.