Fatigue and static behaviour of aluminium box-stiffener lap joints

The fatigue and static behaviour of aluminium box-stiffener lap joints were investigated in this study. Finite element analysis showed that stress concentration factor (SCF) at the weld toe decreased greatly as the weld leg length increased, while the location of the greatest SCF deviated from the connecting point to the middle of the flange. It is also found that the SCF at the weld root is much less than that at the weld toe. Fatigue tests showed that weld toe cracking was the main fatigue failure mode. In addition, fatigue crack initiation site changed from the connecting point to the middle point of the flange. Weld root failure was only possible when the weld leg length was less than twice the main plate thickness (6.0 mm). The test data agree with those for toe failure given by Eurocode 9.