In modern mechanical design, ensuring the strength of welded joints is one of the most difficult challenges. Whether in the automotive industry, the railway sector, or general heavy machinery, the traditional way to check a weld is through physical laboratory testing. However, physical tests are very expensive, slow, and require building many prototypes. While engineers use computer simulations to save time, the most accurate 3D solid models are too slow for large structures like train carriages or vehicle frames. On the other hand, the faster shell models often give incorrect results if they are not analyzed properly. The aim of this study is to create a reliable numerical methodology that allows engineers to use these fast shell models to accurately predict weld breakage and structural failure.