Exploratory Tests on the Effects of Random Loading and Corrosive Environment on the Fatigue Strength of Fillet-Welded Lap Joints

Fatigue tests on simple, fillet-welded, mild steel lap joints have been carried out to determine the effects of a corrosive environment and random loading. At normal testing frequencies, a brine-drip environment had no effect on the constant-amplitude fatigue strength at short endurances. At stresses less than the in-air fatigue limit, the corrosive environment was sufficient to allow crack growth at very low stress levels. In these corrosive environment tests, reducing the test frequency by a factor of 50 halved the life. The results of narrow-band random loading tests could be predicted reasonably accurately either by a fracture mechanics method or by Miner's rule.