Data-driven fatigue assessment of welded engineering structures

In welded joints, fatigue strength is linked to high stress concentrations along weld seams, which makes their detection crucial for ensuring the structural integrity of welds. Manual measurement methods are prone to human error and require extensive time to achieve comparability (Hammersberg and Olsson 2010). In contrast, automated techniques to digitize surface geometries offer efficient and detailed methods to inspect weld profiles. The systems available today for non-destructive optical sur-face measurement (e.g., 3D scanners) and modern computing and storage capacities open up new possibilities for weld quality evaluation and for correlating the weld seam geometry with the expected fatigue strength using data-driven methods. This results in the potential for significant savings in production costs and resources through: Time- and cost-efficient weld seam assessment by inline inspection. High resolution determination of the achieved fatigue strength and quality of the produced weld seam to avoid excessive reworking. Reduction of conservative design of welded joints by considering the actual fatigue strength achieved during production. The goal of this work is to develop a highly accurate data-driven methodology that enables fatigue assessment of welded joints based on optical surface measurement techniques to ensure a high weld quality standard and to reduce the risk of structural failures. The workflow together with suitable engineering structure applications are presented in Fig. 1 together with the three parts discussed in this habilitation. To achieve the overall goal, the following objectives are identified: The development of a methodology for accurate weld geometry measurements that could build the foundation for future automated weld quality assessment approaches. A comparison of available methods for weld geometry measurements to get a better understanding of the scatter involved and what effect this may have on the fatigue strength assessment of welded joints.