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 C(t)-integrals for SE(B) Specimen Under Elastic-Plastic-Creep Conditions

탄성-소성-크리프 상태에서 SE(B) 시편의 천이크리프 C(t)-적분 평가

  • Received : 2015.04.23
  • Accepted : 2015.06.24
  • Published : 2015.09.01
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Abstract

In this paper, we estimate the time-dependent C(t) integrals under elastic-plastic-creep conditions. Finite-element (FE) transient creep analyses have been performed for single-edge-notched-bend (SEB) specimens. 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 exponents in the power-law creep and plasticity to elastic-plastic-creep behavior. To estimate the C(t) integrals, we compare the FE analysis results with those obtained using formulas. In this paper, we propose a modified equation to predict the C(t) integrals for the case of creep exponents that are different from the plastic exponent.

본 논문에서는 탄성-소성-2 차 크리프 상태에서 시간의존적 C(t) 적분에 대해 평가하였다. Single- Edge-notched-Bend (SEB) 시편에 대해 유한요소 크리프 해석을 수행하였다. 천이 크리프에 대한 초기 소성의 영향을 연구하기 위해 다양한 초기 하중에 대해 고려하였다. 또한, 소성물성과 크리프 물성의 영향을 보기 위해 소성 경화 지수(m)과 크리프 지수(n)이 같은 경우와 다른 경우를 모두 고려하였다. 본 논문에서는 기존 식의 수정을 통해서 천이 크리프 상태에서의 C(t) 적분의 새로운 예측 식을 제시하였다. 유한요소해석 결과와 비교를 통해서 제시된 수식의 타당성을 검증하였고, 소성 경화 지수(m)과 크리프 지수(n)이 같은 경우에만 적용할 수 있는 기존 예측 식을 보완하여 m 과 n 이 다른 경우에도 천이 크리프 상태에서 C(t) 적분을 예측할 수 있는 식을 제시하였다.

Keywords

References

  1. Riedel, H., 1987, Fracture at High Temperature, Springer-Verlag, Berlin.
  2. Ainsworth, R. A., 1982, "Some Observations on Creep Crack Growth," International Journal of Fracture Mechanics, Vol. 20, No. 2, pp. 147-159. https://doi.org/10.1007/BF01141263
  3. Ainsworth, R. A. and Budden, P. J., 1990, "Crack Tip Fields Under Non-Steady Creep Conditions-I. Estimates of the Amplitudes of the Fields," Fatigue & Fracture of Engineering Materials & Structures, Vol. 13, No. 3, pp. 263-276. https://doi.org/10.1111/j.1460-2695.1990.tb00598.x
  4. Joch, J. and Ainsworth, R. A., 1992, "The Effect of Geometry on the Development of Creep Singular Fields for Defects Under Step-Load Controlled Loading," Fatigue & Fracture of Engineering Materials & Structures, Vol. 15, No. 3, pp. 229-240. https://doi.org/10.1111/j.1460-2695.1992.tb01266.x
  5. Fujioka, T. and Ainsworth, R. A., 2000, "A Simplified Estimation Method of a Crack Propagation Parameter in Non-Steady Creep," ASME PVP Conference, Seattle, Vol. 412, pp. 75-81.
  6. Kim, Y. J., Dean, D. W. and Budden, P. J., 2001, "Finite Element Analysis to Assess the Effect of Initial Plasticity on Transient Creep for Defects Under Mechanical Loading," International Journal of Pressure Vessels and Piping, Vol. 78, No. 11-12, pp. 1021-1029. https://doi.org/10.1016/S0308-0161(01)00119-3
  7. Webster, G. A. and Ainsworth, R. A., 1994, High Temperature Component Life Assessment, CHAPMAN&HALL, UK.
  8. ABAQUS version 6. 13., 2013, User's Manual, Inc. and Dassault Systems.
  9. Kim, Y. J., 1999, "Evaluation of Time Dependent Contour Integrals (J and C) in Creep: Comparison of ABAQUS and BERSAFE Results," British Energy Generation LTd, Report EPD/GEN/REP/0500/99.
  10. Ehlers, R. and Riedel, H., 1981, "A Finite Element Analysis of Creep Deformation in a Specimen Containing a Macroscopic Crack," ICF5, France, Vol. 2, pp. 691-708.
  11. Hutchinson, J. W., 1968, "Singular Behavior at the End of a Tensile Crack Tip in a Hardening Material," Journal of the Mechanics and Physics of Solids, Vol. 16, pp. 13-31. https://doi.org/10.1016/0022-5096(68)90014-8
  12. Rice, J. R. and Rosengren, G. F., 1968, "Plane Strain Deformation near a Crack Tip in a Power-Law Hardening Material," Journal of the Mechanics and Physics of Solids, Vol. 16, pp. 1-12. https://doi.org/10.1016/0022-5096(68)90013-6
  13. Riedel, H. and Rice, J. R., 1980, "Tensile Cracks in Creeping Solids," American Society for Testing and Materials, Philadelphia, pp. 112-130.
  14. Han, J. J., Kim, Y. J., Jerng, D. W., Nikbin, K. and Dean, D., 2014, "Quantification of Creep Stresses Within HAZ in Welded Branch Juctions," Fatigue & Fracture of Engineering Materials & Structures, Vol. 38, No. 1, pp. 113-124. https://doi.org/10.1111/ffe.12223