Abstract
Welded joints are sensitive to fatigue failure due to cyclic loading, as well as fatigue crack propagation influenced by the distribution of welding residual stress. In this study, the fatigue crack propagation rates in butt-welded joints for 304 stainless steel sheets were evaluated in the presence of welding residual stresses. The analysis consisted of two separate models: first, a 3D-finite element (FE) model was used to predict the residual stresses due to welding; second, a numerical study was undertaken to predict fatigue crack propagation in the presence and absence of residual stress using the extended finite element method (XFEM). The crack growth model (NASGRO) and available experimental data were applied to verify the simulation results. The XFEM without residual stress effects shows good agreement with the experimental data and the NASGRO model. However, in the presence of residual stress, the simulation results show less agreement with the NASGRO model. The level and the nature of residual stress have significant effects on crack growth. A faster crack propagation rate is recognized due to the effect of tensile residual stress at the crack tip, while a higher resistance to crack growth is developed due to a compressive residual stress field.
Highlights
Assessment of welded joints is based on numerous factors such as weld geometry; loading type and, residual stress which can produce an extensive impact on the fatigue performance of welded components [1]
Elshrief et al [10] studied the influence of welding residual stress and crack orientation on determining the stress intensity factor for butt steel joints using the XFEM
The fatigue crack growth rate can be rewritten as: da dn. It is evident from equations (7) and (8) that the effective stress ratio will frequently change as the crack propagates due to residual stress, while the total stress intensity factor for the residual and applied external stresses Keff does not need to be considered
Summary
Assessment of welded joints is based on numerous factors such as weld geometry; loading type and, residual stress which can produce an extensive impact on the fatigue performance of welded components [1]. The fatigue crack growth rate may increase due to tensile residual stress and decrease due to compressive residual stress [3]. Liljedahl et al [6] explored the progression of residual stresses with crack growth for compact tension (CT) and middle tension (MT) specimens using a neutron diffraction technique. Ferro et al [8] proposed a model to evaluate the effect of residual stresses on the fatigue life of butt-welded joints by considering the influence of fatigue loading on the redistribution of residual stress. Elshrief et al [10] studied the influence of welding residual stress and crack orientation on determining the stress intensity factor for butt steel joints using the XFEM. We aimed to simulate fatigue crack growth in 304 stainless steel before and after welding, under a cyclic fatigue load, taking into consideration residual stress distribution
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