Fatigue behavior of hybrid multi-bolted-bonded single-lap joints in woven composite plates

The fatigue behavior of Hybrid bolted-bonded (HBB) joints is compared with that of only-bolted (OB) joints. Single-lap shear joints fabricated using carbon fiber-reinforced composites with one, two, and three bolts are investigated. The fatigue life of an HBB joint comprises two stages: the first stage corresponds to the fatigue of a bonded joint. The second stage begins when the adhesive fails and corresponds to the fatigue of a bolted joint. The adhesive debonding is progressive. The fatigue life of the HBB joints after the adhesive has debonded is significantly higher than that of equivalent OB joints. For HBB three-bolt assemblies, the integrity of the adhesive between the outer bolts is maintained throughout the fatigue test, and the final failure is caused by the net tension at the outer bolt. Removing the center bolt does not reduce the fatigue life of HBB joints. This implies that multi-bolt assemblies subjected to fatigue can benefit significantly from hybridization while reducing the number of bolts.