Today, spot-welding is the typical joining technique for steel sheet in the motor car industry. A common laboratory specimen geometry used to evaluate the fatigue resistance of spot-welded steel sheet is the single-lap (or tensile- shear) configuration. The influence of various parameters on the fatigue resistance of single-lap spot-welds are reviewed. However, the results of such tests are difficult to apply quantitatively to design because they are strongly dependent on the specimen dimensions, details of gripping, and magnitude of the maximum load relative to the yield (or plastic collapse) load. Analytical modeling is used herein to attempt to bring into agreement data from many investigators. Models included the nominal axial stress range, range of stress intensity factor, nominal axial load plus first-order bending theory, and nominal axial load plus second-order bending theory. The models are compared with one another using data from the literature for fatigue tests on single-lap specimens with one or two spot-welds on the longitudinal axis of the specimen and for both uncoated and coated steels.

"Modeling of the Fatigue Resistance of Single Lap Spot Welded Steel Sheet," IIW Document III-1469-92, May 1992.