Influence of crack tip plasticity on fatigue behaviour of laser stake-welded T-joints made of thin plates

Research output: Contribution to journalArticleScientificpeer-review


Research units

  • Kyoto University
  • University of Padova


The paper investigates the crack tip plasticity of laser stake-welded T-joints when the thickness is varied. For thin joints, mixed-mode condition is dominant, and the Minimum Plastic Zone Radius (MPZR) criterion is employed to estimate the crack initiation direction. Subsequently, the same first-order plastic zone size ry as defined by Irwin is kept equal for the selected load levels in the MPZR direction, and finite element (FE) analyses are carried out to investigate the stress gradient over ry comparing different thicknesses. The results allow us to explain why the fatigue slope m is different for thin and thick joints. Moreover, a new method is proposed that permits the number of cycles to failure of thin joints to be derived directly from the fatigue curve of thick joints, employing an effective J-integral. The results prove that the method is able to give an estimation of the number of cycles to failure for thin joints with acceptable error.


Original languageEnglish
Pages (from-to)112-123
Number of pages12
JournalInternational Journal of Mechanical Sciences
Publication statusPublished - 1 Feb 2018
MoE publication typeA1 Journal article-refereed

    Research areas

  • Crack, Fatigue assessment, Laser stake-welds, Plastic zone, Slope of fatigue curve

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ID: 17034733