Elastic-plastic fracture mechanics analyses of circumferential through-wall cracks between elbows and pipes

Chang Kyun Oh, Tae Kwang Song, Yun Jae Kim, Jong Sung Kim, Tae Eun Jin

Research output: Contribution to journalArticlepeer-review

9 Citations (Scopus)


The present work proposes a method for elastic-plastic fracture mechanics analysis of the circumferential through-wall crack in weldment joining elbows and attached straight pipes, subject to in-plane bending. Heterogeneous nature of weldment is not explicitly considered and thus, the proposed method assumes cracks in homogeneous materials. Based on small strain finite element limit analyses using elastic-perfectly plastic materials, closed-form limit loads for circumferential through-wall cracks between elbows and straight pipes under bending are given. Then applicability of the reference stress-based method to approximately estimate J and crack opening displacement (COD) is evaluated. It was found that the limit moments for circumferential cracks between elbows and attached straight pipes can be much lower than those for cracks in straight pipes, particularly for a crack length of less than 30% of the circumference; this result is of great interest in practical cases. This result implies that, if one assumes that the crack locates in the straight pipe, limit moments could be overestimated significantly, and accordingly, reference stress-based J and COD could be significantly overestimated. For the leak-before-break analysis, accurate J and COD estimation equations based on the reference stress approach are proposed.

Original languageEnglish
Pages (from-to)1231-1250
Number of pages20
JournalEngineering Fracture Mechanics
Issue number5
Publication statusPublished - 2008 Mar


  • Circumferential through-wall crack
  • Crack opening displacement
  • Elbow
  • Finite element analysis
  • J-integral
  • Leak-before-break
  • Reference stress method

ASJC Scopus subject areas

  • Materials Science(all)
  • Mechanics of Materials
  • Mechanical Engineering


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