Abstract
We proposed a method for analyzing the sensitivity of the nugget diameter to the nominal structural stress, and conducted a fatigue test to verify the results of the sensitivity analysis. The proposed method was confirmed to provide a good solution. The nugget diameter sensitivity S_d differs according to the general load components. The nugget diameter sensitivity S_<Nde> to fatigue life showed a good correlation with the estimated value of the standard deviation of the logarithm of the fatigue life, and it was demonstrated that the fluctuations in fatigue life resulting from variations of the nugget diameter can be assessed using S_<Nde>.
