PSI - Issue 41

A.L. Ramalho et al. / Procedia Structural Integrity 41 (2022) 412–420 Author name / Structural Integrity Procedia 00 (2019) 000–000

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In this approach the crack length increment, Δ a 0 , was prescribed and the corresponding number of fatigue cycles, N, was calculated by the integration of Paris-Erdogan Law (4), assuming a linear variation of the stress intensity factors K along the increment of the crack. 3. Results and discussion 3.1. Fatigue crack propagation In figures 3(a) and 3(b) are presented the von Mises stress and the longitudinal plastic strain fields (ε pxx ), generated by TIG dressing, respectively. There is a well-defined peak of stresses and strains at the root of weld toe, induced by the thermal process. The maximum values of stresses are above 500 MPa. Along the width of the specimen, there is no significant variation in the stresses. The field of stresses and deformation are similar and in good agreement with the results presented by other authors, Barsoum and Barsoum (2009) and Yuan and Sumi (2013). The estimated residual stresses, σ xx , near the weld toe were compared with the ones obtained by Ramalho et al. (2020). Figure 4 presents the variation of σ xx residual stresses versus the distance x. The increase of x distance produces an increase of residual stresses up to a peak, followed by a progressive decrease. A good agreement is observed between the numerical predictions and experimental values obtained by X-ray diffraction and hole drilling technique, which validates the numerical procedure. x toe corresponds to the position of the weld toe, measured from the symmetry plane, being used to allow comparison between different specimens.

Fig. 3. (a) Estimated von Mises residual stress field [Pa]; (b) Estimated longitudinal plastic strain fields.

Fig. 4. Comparison between the estimated residual stresses and those obtained experimentally.