Investigation of Welded Joints in Finite Element Analysis

Regions with the lowest fatigue life in a welded joint are usually formed at the weld toe or weld root. It is important to carefully examine the welded joint region, especially for structures exposed to high moments and forces. While evaluating welded joints in finite element method (FEM) analysis, it can be evaluated according to International Institute of Welding (IIW). According to IIW, there are four approaches to evaluate the stresses on the welded joint: the nominal stress approach, the structural hot spot stress approach, the effective notch stress approach and the linear elastic fracture mechanics' approach. In large and complex structures, modeling of welded joints in FEM analyzes affects the time spent for analysis. Therefore, preferred approach for modeling and evaluation is important for the time spent. The accuracy rate, on the other hand, varies according to the chosen approach, and investigations should be made according to the complexity of the structure being analyzed and the type of stress coming to the examined region. Although the accuracy rate is closest to the linear elastic fracture approach, this approach is not preferred because it will require a lot of effort in FEM analysis, especially in complex structures. In this study, conventional approaches proposed by IIW were examined while performing welded joints in FEM analysis. These investigations were carried out in the welded region with the most critical stress on a mobile crane machine. According to the results of the study, the hot spot stress was found to be 693 MPa and the nominal stress was 515 MPa according to the maximum principal stress in this region.