• 대한기계학회논문집
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• 제10권3호
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• pp.292-297
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• 1986

본 연구에서는 2024 Al 합금에 대하여 260-380.deg. C의 온도 범위 및 2~5kgf/ m $m^{2}$의 부과응력 범위에서 실시한 고온 정상 크리이프 변형 중의 내부응력 .sigma. $_{i}$,의탄성 변형 .epsilon.$_{A}$ 및 회복율 r의 측정 실험을 통하여 이들 상호간의 관계 를 살펴 보고자 한다.다.다.

• Structural Engineering and Mechanics
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• 제15권4호
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• pp.395-414
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• 2003

In this paper we recall briefly the constitutive equations for solids subjected to thermal strain taking in account the bounded tensile stress of the material. In view to solve the equilibrium problem via the finite element method using the Newton Raphson procedure, we show that the tangent elasticity tensor is semi-definite positive. Therefore, in order to obtain a convergent numerical method, the constitutive equation needs to be modified. Specifically, the dependency of the stress by the anelastic deformation is made explicit by means of a parameter ${\delta}$, varying from 0 to 1, that factorizes the elastic tensor. This parameterization, for ${\delta}$ near to 0, assures the positiveness of the tangent elasticity tensor and enforces the convergence of the numerical method. Some numerical examples are illustrated.

• 한국해양공학회지
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• 제6권1호
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• pp.78-86
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• 1992

The creep behaviors of 1%Cr-Mo-V and 12%Cr steam turbine rotor steels under static or cyclic load were examined at 600 and $700^{\circ}C$. The relationship between these two kinds of phenomena was studied and the experimental results were summarized as follows: 1) It is confirmed that the cyclic creep strain dependent on time is more available for creep, behavior analysis according to frequency change than that dependent on number of cycles, and the static creep, the special case of cyclic creep with stress ratio of 1 can be also more effectively analyzed by time-dependence. 2) The steady cyclic creep rate vs. the steady static creep rate, increases according to the increase of stress ratio, and this phenomena may occur on occasion of the decrease of the internal stress. 3) The initial strain affects on all the creep properties of the transient region, the steady state region and the rupture time in cyclic creep as well as static creep, and the quantitative relationships among them exist.