Investigation of residual stresses in a longitudinal gusset joint using welding simulation and qualitative Barkhausen Noise analysis

The effect of residual stresses on fatigue performance has been known for decades and considered in fatigue assessments, for example, conducting mean stress corrections. However, based on simulations and in-situ field measurements, there might be considerable variation in the residual stresses after fabrication, introducing uncertainty in the determination of computational life assessments. To fully utilise the fatigue capacity of welded structures, the uncertainty related to the residual stress state must be addressed. In specific fatigue-critical areas, unfavourable high tensile residual stresses can be avoided by local post-treatments, such as thermal stress relief techniques and/or mechanical treatments. However, in larger, highly-stressed weldments, post-weld treatments are not practical or cost-effective, creating a need for more accurate predictability or determination of residual stresses. In this study, welding of the longitudinal gusset was simulated by finite element modelling, considering different mechanical boundary conditions and geometrical stiffness of the joint. Both factors were found to affect the resulting residual stress distribution clearly. In addition, the suitability of the Barkhausen Noise analysis for verifying the residual stress state in welded structures as a qualitative measurement method was investigated.