Evaluation of local stress-based fatigue strength assessment methods for
welded structures subjected to axial and bending loading
Abstract
The current study aims to find suitable fatigue assessment methods for
welded structures (cover plates and T-joints) subjected to axial and
bending loading. For this purpose, the Hot Spot Stress method (HSS),
1-mm stress (OM) method, Theory of Critical Distances (TCD) method,
Stress Averaging (SA) method, and Effective Notch Stress (ENS) method
are evaluated in terms of accuracy and reliability. The evaluation is
based on fatigue test data extracted from the literature and fatigue
testing carried out in the current study; cover plate joints subjected
to axial loading and T-joints subjected to bending. The notch stress
methods have higher estimation accuracy for the cover plate joints
subjected to axial loading than the structural stress methods. It is
found that the SA method can be used to assess the fatigue strength of
cover plate joints with good accuracy and low scatter, followed by the
ENS method. The fatigue strength assessment of T-joints subjected to
bending using the HSS method, TCD method, SA method, and ENS method and
corresponding FAT class is conservative, whilst the accuracy is low.
Fatigue design curves applicable for T-joints under bending are
introduced and described, which can be used in the TCD method, SA
method, and ENS method.