| Project/Area Number |
60460201
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| Research Category |
Grant-in-Aid for General Scientific Research (B)
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| Allocation Type | Single-year Grants |
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| Research Field |
金属材料(含表面処理・腐食防食)
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| Research Institution | NIIGATA university |
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Principal Investigator |
FURUKAWA Toru NIIGATA university, Faculty of Engineering,Professer, 工学部, 教授 (90018458)
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| Co-Investigator(Kenkyū-buntansha) |
KONUMA Shizuyo NIIGATA university, Faculty of Engineering. Assistant, 工学部, 助手 (50018496)
SUZUKI Kenzi NIIGATA university Faculty of Education, Lecturefr, 教育学部, 講師 (30154537)
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| Project Period (FY) |
1985 – 1987
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| Project Status |
Completed (Fiscal Year 1987)
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| Budget Amount *help |
¥8,700,000 (Direct Cost: ¥8,700,000)
Fiscal Year 1987: ¥600,000 (Direct Cost: ¥600,000)
Fiscal Year 1986: ¥700,000 (Direct Cost: ¥700,000)
Fiscal Year 1985: ¥7,400,000 (Direct Cost: ¥7,400,000)
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| Keywords | Surface Hardening / Fatigue limit / Fatigue Mode / Notch Shape / Stress Concentration Factor / Non-Propergating Crack / Stress Intensity Factor / 余寿命 / 切欠き形状 / 段付き軸 |
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| Research Abstract |
The influence of the surface hardening conditions (surface hardness,core harhness effective case depth (E C D).etc) and the notch shape (stress concentration factor <alpha> ) on the rotating bending fatigue properties (fatigue limit,crack initiation strength, initiation and propagation of fatigue crack. non-propagating crack, etc) and the fracture mode of surface hardened steel were investigated and those mutual relationshipe were analyzed. Thersults obtained are summarized as followes :
1) The fatigue limit is directly influenced E C D, the core hardness and <alpha> ,and the fracture mode (inner origin type fracture of surface origin type fracture ) is changed by these factors,therefore the fatigue limit is influenced by the change of the fracture mode.
2) In the case of the inner origin type fracture, the increase of E C D, the core hardness,or <alpha> makes the fatigue limit higher and induces the change of the fracture mode from the inner origin thpe to the surface origin type. When the inner origin type fracture changes to the surface origin type fracture, the fatigue limit becames the maximum value. The reason is that the fracture initiation becames deep with increasing E C D the increase of the core hardness makes the crack initiation strength higher, and the applied stress at the inner part dereases wity inreasing <alpha>. The increase of <alpha>. E C D and the core hardness after the maixmum value of the fatigue limit makes the fracture mode the surface origin type fracture and dereases the featigue limit.
3) In the case of the surface origin type fracture, the fatigue decreased with increasing <alpha> E C D and the core hardness. The reason is that the applied stress at the notch root becomes higher wigh increasing <alpha> and the residual compressive stress at the notch root decreases with increasing E C D and the core hardness. However when <alpha> exceeded a certain value non-propagating cracks were recognized and the fatigue almost constant.
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