• 대한기계학회논문집
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• 제14권6호
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• pp.1568-1575
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• 1990

본 연구에서는 중앙균열을 가진 SB41강의 평판이 하중제어와 변형률제어 피로 상태에서 소규모 항복, 대규모 항복, 또는 전면 항복의 각 응력에서 피로균열 진전 속 도와 J적분 범위, .DELTA.J와의 관계를 조사하는 한편, 피로균열 진전 속도를 지배하는 국 소적 역학 인자인 균열선단 개구변위, COD와 균열 진전 속도와 관계 및 그 특성을 고 찰하였다.

• 한국해양공학회지
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• 제9권2호
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• pp.98-111
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• 1995

High temperature low cycle fatigue shows that cycle-dependent crack growth owing to cyclic plastic deformation occurred simultaneosly with time-dependent crack growth owing to intergranular deformation. Consequently, to estimate crack growth rate uniquely, many to investigators have proposed various kinds of parameters and theories but these could not produce satisfactory results. Therefore the goal of this study is focused on prediction of crack growth rate using predominant damage rule, linear cumulative damage rule and transitional parameter ${\Delta}J_c/{\Delta}J_f$. On the basis of these sinusoidal loading waveform at 600$^{\circ}C$ and 700$^{\circ}C$.

• 대한기계학회논문집
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• 제15권3호
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• pp.916-923
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• 1991

본 연구에서는 표면 균열이 있는 평판의 탄소성 피로하중 상태에서 성장하는 균열 형태의 변화와, 작용하는 응력의 크기에 따른 균열 개페구 특성의 변화를 연구하 였다.또, 유효 응력 확대계수 범위, .DELTA.K$_{eff}$와 J적분범위, .DELTA.J가 탄소성 응력 상태에서의 표면 피로균열 진전속도를 나타내는 역학양으로 사용되는데 따른 적합성등 을 검토하였다.

• 대한기계학회논문집
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• 제18권3호
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• pp.548-554
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• 1994

The high temperature fatigue crack growth behavior of SUS 304 stainless steel at $550^{\circ}C$ and $650^{\circ}C$ was investigated under various kinds of stress ratio and frequency in sinusoidal waveform on the basis of the non-linear fracture mechanics. The result arranging crack growth rate by modified J-integral J' showed influence of stress ratio and frequency. All the data obtained under the test at $550^{\circ}C$ were plotted within data band of da/dN-${\triangle}J_f$ relationship for cycle-dependent crack growth. On the basis of static creep and cycle-dependent data band; both time- and cycle-dependent crack growth behavior was observed under loading conditions at $650^{\circ}C$, but cycle-dependent crack growth behavior predominantly appeared and time-dependent crack growth behaviour was little observed under loading conditions at $550^{\circ}C$. Fractographic examinations for fracture surface indicated that the fracture mode was generally transgranular. The stripes were found on fracture surface and each stripe was accompanied by a crack tip blunting and an abrupt increase in the load-point displacement. The $J'_{an}$ had a validity in case of $650^{\circ}C, but scarcely had it in case of $550^{\circ}C$.