Fatigue life estimation based on fracture mechanics of single spot welded joints under different loading modes

To evaluate the accuracy of joint fatigue life estimations obtained using conventional theories, the fatigue properties of shear- and peel-type single spot welded joints were investigated experimentally and analytically. The observed crack initiation angles differed from the predictions obtained using conventional theories, indicating that the theories cannot be used to evaluate the fatigue properties of the joints. In contrast, the present analytical crack initiation angles were in good agreement with the experimental results. Therefore, the effect of the loading mode on the fatigue properties of the single spot welded joints was adequately determined from the range ΔKI,θmax of initial stress intensity factors thorough an analytical evaluation.