Evaluation of local stress-based fatigue strength assessment methods for cover plates and T-joints subjected to axial and bending loading

This study aims to find suitable fatigue assessment methods for welded structures (cover plates and T-joints) subjected to axial and bending loading. The Hot Spot Stress (HSS), 1-mm stress (OM), Theory of Critical Distances (TCD), Stress Averaging (SA), and Effective Notch Stress (ENS) methods are evaluated in terms of accuracy and reliability. The evaluation is based on fatigue test data extracted from the literature and carried out in this study. It is found that the SA method can be used to assess the fatigue strength of cover plate joints under axial loading with relatively good accuracy and low scatter, followed by the ENS method. The HSS, TCD, SA, and ENS methods are conservative estimation methods for T-joints under bending, while the accuracy is low. Furthermore, fatigue design curves applicable for T-joints under bending are discussed, which can be used in the TCD method and SA method.