Transactions of the Korean Society of Mechanical Engineers A (대한기계학회논문집A)

The Korean Society of Mechanical Engineers (대한기계학회)
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Estimation of Transient Creep Crack-tip Stress Fields for SE(B) specimen under Elastic-Plastic-Creep Conditions

탄성-소성-크리프 상태에서 SE(B) 시편의 천이크리프 균열 선단 응력장 평가

  • Lee, Han-Sang (Department of Mechanical Engineering, Korea Univ.) ;
  • Je, Jin-Ho (Department of Mechanical Engineering, Korea Univ.) ;
  • Kim, Dong-Jun (Department of Mechanical Engineering, Korea Univ.) ;
  • Kim, Yun-Jae (Department of Mechanical Engineering, Korea Univ.)
  • Received : 2015.05.06
  • Accepted : 2015.06.28
  • Published : 2015.10.01
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Abstract

This paper estimates the time-dependent crack-tip stress fields under elastic-plastic-creep conditions. We perform Finite-Element (FE) transient creep analyses for a Single-Edge-notched-Bend (SEB) specimen. We investigate the effect of the initial plasticity on the transient creep by systematically varying the magnitude of the initial step-load. We consider both the same stress exponent and different stress exponent in the power-law creep and plasticity to determine the elastic-plastic-creep behaviour. To estimation of the crack-tip stress fields, we compare FE analysis results with those obtained numerically formulas. In addition, we propose a new equation to predict the crack-tip stress fields when the creep exponent is different from the plastic exponent.

본 논문에서는 탄성-소성-크리프 상태에서 시간의존적 균열 선단 응력장을 평가하기 위해 Single-Edge-notched-Bend (SEB) 시편을 사용하여 유한요소 크리프 해석을 수행하였다. 천이크리프의 초기소성 영향을 조사하고자 다양한 초기하중을 대해 고려하였으며, 또한 소성물성과 크리프 물성의 영향을 조사하기 위해 소성 경화 지수(m)과 크리프 지수(n)이 같은 경우와 다른 경우를 모두 고려하였다. 결과로서, 기존 식의 수정을 통해서 천이크리프 상태에서의 균열 선단 응력장의 예측 식을 제안하였으며, 유한요소해석 결과와 비교를 통해서 제시된 수식의 타당성을 검증하였다. 그리고 m 과 n 이 같은 경우뿐만 아니라 m과 n이 다른 경우에도 천이크리프 상태에서 균열 선단 응력장을 예측 할 수 있는 식을 제안하였다.

Keywords

References

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