Numerical simulations of fatigue crack initiation and propagation based on re-tensile plastic zone generating load criterion for in-plane gusset welded joints

Yukinobu Nagata, Koji Gotoh, Masahiro Toyosada

Research output: Contribution to journalArticle

4 Citations (Scopus)


Many accidents are caused by fatigue in welded built-up steel structures, and so it is important to estimate the fatigue lives of such structures quantitatively for safety reasons. By assuming that fatigue cracks cannot grow without an accumulation of alternating tensile/compressional plastic strain, one of the authors identified an improved effective stress intensity factor range ΔK RPG based on the re-tensile plastic zone generating (RPG) load, which represents the driving force for fatigue cracks, and suggested that ΔK RPG should be used as the parameter to describe fatigue crack growth behavior. The "FLARP" numerical simulation code in which ΔK RPG is implemented as the fatigue crack growth parameter, was developed in order to predict fatigue crack initiation and propagation behavior. In this paper, it is demonstrated that FLARP gives accurate estimates for fatigue life by comparing the estimated fatigue crack growth curves and S-N curves with the experimental results for in-plane gusset welded joints, which are used in many welded steel structures. Moreover, the effect of induced bending moment due to the linear misalignment in the out of plane direction on the fatigue strength of in-plane gusset welded joints is investigated through numerical simulations.

Original languageEnglish
Pages (from-to)104-114
Number of pages11
JournalJournal of Marine Science and Technology
Issue number1
Publication statusPublished - Mar 2009


All Science Journal Classification (ASJC) codes

  • Ocean Engineering
  • Mechanics of Materials
  • Mechanical Engineering
  • Oceanography

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