Use of infrared thermography to model the effective stress ratio effect on fatigue crack growth in welded T-joints

•Fatigue tests on T-welds are monitored using thermoelastic stress analysis.•A fatigue crack closure phenomenon is observed via thermometry.•Residual stresses evolution explains the various observed crack closure ratio.•A fatigue crack growth model is assessed through thermoelastic stress analysis.•This model proposes an original approach to account for the effective stress ratio. Welded joints constitute critical components in the high-cycle fatigue dimensioning of naval structures. In particular, the local geometry of the weld toe as well as the welding process induced residual stress strongly impact the fatigue properties. In that regard, such factors must be considered in a dedicated fatigue life forecast model, identified via an adapted experimental protocol. On the basis of X-ray stress analysis and in-situ crack growth monitoring by thermoelastic stress analysis, the present study introduces a linear elastic fracture mechanics model that considers the initial residual stress field in the vicinity of the weld toe.