Fatigue tests of the specimen designed according to the typical interconnected structures of a certain airplane’s wing box were carried out to analyze the effects of different assembly processes of high locked bolts on fatigue performance. The results show that the fatigue performance of interconnected structures can be improved effectively by exerting an appropriate second–tightening torque to high locked bolts after the current assembling processes. A three–dimensional finite element model was established to investigate the effects of tightening torque of bolts

friction coefficient between plates as well as elastic modules of bolts on the stress concentration factor of the hole edge in basic plates. The study indicates that all the three factors have great influence on the stress concentration factor of the hole edge. Furthermore

tightening torque of bolts has the most significant impact. It also shows that exerting a second–tightening torque is an effective mean to improve the fatigue performance of interconnected structures.