is similar in both cases and accepts similar tolerances, making it easier to replace the joining technology, requiring less effort compared to d other assembly concepts that require new design principles and a new concept of tolerance management. However, this transition using overlap welding provides a modest weight saving compared to FSW butt joint configurations. In large fuselage panels, achieving the tight tolerances required for FSW butt joints poses a significant assembly challenge that can limit the application of this configuration, preventing its application for major component assembly and assembly final. When it comes to FSW lap joints, research and development is not as exhaustive as for FSW butt joints and there is a lack of knowledge about the mechanical performance of this configuration. However, published studies conclude that there is a clear disadvantage of FSW overlap joints. The unwelded interface of lap sheets, which is disrupted by the vertical flow of material during the process, creates a reduction in effective cross-sectional area and an increase in stress concentration....