Post-processing of 3D-scanned welds for a structural simulation-based fatigue life prediction

The fatigue life of welded components can be assessed using finite element simulations and fatigue damage parameters. The underlying models are often based on idealized weld geometries, although the real-world geometry of hand-welded seams can deviate substantially from these idealized geometries, particularly in notch regions that are critical for fatigue crack initiation. Although 3D-scanning has already been used to implement the real weld geometry in numerical fatigue assessment, the influence of scan post-processing, meshing, and material modeling is often not documented in sufficient detail. As a result, it remains scientifically unclear how strongly these parameters affect the calculated simulation results. This study provides detailed and reproducible guidance for fatigue life assessment based on 3D-scanned weld geometries using commercial and widely available tools and highlights the main modeling decisions. The results show that the crack path on the weld surface can be predicted well and that damage parameters accounting for the stress gradient improve fatigue life prediction by a factor higher than 10. Furthermore, the influence of post-processing and smoothing of the specimen surface is shown to be significant as it has the potential to nearly halve the deviation when using the FDP SWT . The prediction quality of the processed 3D-scanned geometries is also compared with that of idealized geometries. With the currently available damage parameters, fatigue life prediction based on the idealized geometry is still more precise and shows less scatter than those based on 3D-scanned geometries.