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On Relevant Ramberg-Osgood Fit to Engineering Non-Linear Fracture Mechanics Analysis

정확한 비선형 파괴역학 해석을 위한 Ramberg-Osgood 상수 결정법

  • 허남수 (성균관대학교 기계공학부) ;
  • 김윤재 (성균관대학교 기계공학부) ;
  • 최영환 (한국원자력안전기술원) ;
  • 양준석 (한국전력공사 전력연구원) ;
  • 김영진 (성균관대학교 기계공학부)
  • Published : 2003.09.01

Abstract

This paper proposes a robust method for the Ramberg-Osgood(R-O)fit to accurately estimate elastic-plastic J from engineering fracture mechanics analysis based on deformation plasticity. The proposal is based on engineering stress-strain data to determine the R-O parameters, instead of true stress-strain data. Moreover, for practical applications, the method is given not only for the case when full stress-strain data are available but also for the case when only yield and tensile strengths are available. Reliability of the proposed method for the R-O fit is validated against detailed 3-D Finite Element (FE) analyses for circumferential through-wall cracked pipes under global bending using five different materials, three stainless steels and two ferritic steels. Taking the FE J results based on incremental plasticity using actual stress-strain data as reference, the FE J results based on deformation plasticity using various R-O fits are compared with reference J values. Comparisons show that the proposed R-O fit provides more accurate J values for all cases, compared to existing methods for the R-O fit. Advantages of the proposed R-O fit in practical applications are discussed, together with its accuracy.

Keywords

Crack Opening Displacement;Leak-Before-Break;J-Integral;Circumferential Through-Wall Crack

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