Stress field and fatigue strength analysis of 135-degree sharp corners based on notch stress strength theory

Fatigue strength is known to be closely related to the precise geometrical discontinuity of the welded joints. It is necessary to better understand the fatigue behavior of welded joints with consideration of the geometrical factors that produce locally high stresses. Based on notch stress strength theory, this paper proposes a simple method using the singularity strength 'as' to estimate the stress field distribution at the corner. By comparing the expected results of 135° sheet corner with those obtained by N-SIF formula, the contribution of the singularity strength 'as' is quantified for different geometries, and summarized into concise expressions. Subsequently, the stress field parameters, namely the notch stress intensity factors (N-SIFs), are combined with 'as' formula to predict the fatigue strengths of cruciform weldments. Validity of this method is further verified by analyzing the fatigue test results for several cruciform welded joints reported in literatures. The results show that the proposed 'as' method has the additional advantage in simplified stress field and fatigue strength estimation for welded joints.