In this paper, the influence of simultaneous variation of nugget diameter and spot welding location on fatigue life of the spot-welded joints was investigated under two kinds of loading, tensile shear and bending. The relationship between spot welding position and the nugget diameter and the nominal structural stress, which is used as fatigue life evaluation parameters, were examined. The variation of fatigue life due to varying the influence factors was quantitatively assessed by the sensitivity analysis. The fatigue test was conducted to verify the results of the sensitivity analysis. As a result, it was shown that the influence of the factors of the variation to the fatigue life was able to be accurately evaluated using the sensitivity.
