Evaluation of Creep-Fatigue Behavior under Multiaxial Loading Based on the Overstress Concept
| Project/Area Number |
63460076
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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 |
材料力学
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| Research Institution | The University of Tokyo |
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Principal Investigator |
ASADA Yasuhide University of Tokyo, Dept. of Mech. Eng. Prof., 工学部, 教授 (20011091)
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| Co-Investigator(Kenkyū-buntansha) |
NITTA Yasuwo University of Tokyo, Dept. of Mech. Eng. Asst., 工学部, 助手 (60011087)
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| Project Period (FY) |
1988 – 1989
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| Project Status |
Completed (Fiscal Year 1989)
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| Budget Amount *help |
¥5,100,000 (Direct Cost: ¥5,100,000)
Fiscal Year 1989: ¥1,100,000 (Direct Cost: ¥1,100,000)
Fiscal Year 1988: ¥4,000,000 (Direct Cost: ¥4,000,000)
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| Keywords | Multiaxial Stress / Creep-Fatigue / Overstress / Internal Stress / 304 Stainless Steel / Environmental Effect / 304ステンレス鋼 / クリープ疲労相互作用 |
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| Research Abstract |
A research has been made in order to establish a creep-fatigue life prediction procedure under multiaxial loading condition. Deformation and failure behaviors under the multiaxial creepfatigue condition were studied in detail. Hollow cylindrical test specimens were prepared with solution annealed 304 stainless steel and were subjected to a strain controlled tension-torsion under proportional loading at 650ﾟC in air. Additionally, uniaxial push-pull strain controlled creep-fatigue tests were also made with the same test material at 650ﾟC in air and in high vacuum environment.
Analyses were made with stress-strain responses of the test results to obtain the overstress and the internal stress in order to make clear the relation between the inelastic deformation behaviors and those components of stress.
A development of anisotropy was observed with the overstress and the internal stress even though the peak stresses showed isotropy. The time dependent behavior of the overstress showed a chan
… More
ge due to the ratio of normal versus shear overstress components. It was concluded that the shear component of the overstress controls the time-independent component of the inelastic deformation and that the normal component of the overstress controls the time-dependent component of the inelastic deformation. Additionally, It was made clear that the stress relaxation behavior is composed of, at least, two components: one is the relaxation of the overstress and the other is the relaxation of the internal stress. The former occurs with a high stress relaxation rate to cease within a short time duration,, however, the latter has a slow relaxation rate to last for long time.
Regarding the creep fatigue failure behavior, the inelastic strain integration of the overstress controls the time-independent component of the creep-fatigue damage. Furthermore, The maximum resolved shear component of the overstress controls the environment free component of the damage. The environmental effect is included in the time-independent damage component and is governed by a resolved normal component of the overstress.
The time-dependent component of the damage is well described with the time integration of the maximum principal overstress component. Obtained is the creep-fatigue life prediction equation which is available for the multiaxial loading condition including the environmental effect. Less
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Report
(3 results)
Research Products
(15 results)
