Calibration and validation of analytical heat source models for hybrid laser beam welding and GMAW applications in naval structures

Abstract

Welding technology plays a crucial role in the construction of ships and offshore structures, where the selection of an appropriate welding process directly affects production efficiency, structural reliability, and overall lifecycle costs. Gas metal arc welding is widely applied in shipyards due to its high flexibility; however, it involves a comparatively large heat input, leading to extensive heat-affected zones, distortion, and residual stresses that increase rework and maintenance costs. In contrast, laser beam welding offers high welding speeds and reduced heat input, but its industrial application is limited by the requirement for very small joint gaps and tight tolerances. Hybrid laser-arc welding (HLAW) combines the advantages of both processes, overcoming their individual drawbacks and thus providing an efficient solution for the production of such structures.

However, despite the progress made in recent decades, there is still no analytical model available that is capable of realistically describing the welding process in all its complexity. In order to better capture and understand the influence of temperature distributions arising from HLAW, an analytical model is indispensable. Such a model would make it possible to investigate and predict characteristic welding features, most notably the fusion zone and the surrounding heat-affected zone. Beyond describing the weld geometry itself, the development of a reliable analytical model would also provide a valuable tool for analyzing thermally induced distortions and residual stresses, which strongly influence component quality in practice. Compared to numerical approaches, analytical models offer the decisive advantage of significantly reduced computational costs, which enables fast predictions and preliminary assessments.

In this work, an analytical model for the prediction of welding-induced temperature fields in finite-thickness plates under convective boundary conditions is extended by introducing a second heat source to approach HLAW applications. Both the arc and laser contributions are represented by Goldak’s double-ellipsoidal heat source model. To reproduce keyhole mode welding characteristics, a vertical offset of the laser heat source is introduced. The heat source parameters are calibrated against experimental fusion zone geometries using a dedicated optimization framework. Finally, the results are validated through finite element analysis, demonstrating good agreement of the analytical model for describing HLAW conditions.