Effect of water absorption on the adhesive damage in bonded composite repair of aircraft structures

• The water absorption increases the extent of the adhesive damaged zone.
• The water absorption reduces the fatigue life of repaired structures.
• The risk of the adhesion failure increases with the water absorption by the adhesive.

In this study, the mechanical properties of the aged adhesive Adekit A140 epoxy were used in a finite element model to evaluate the effect of water absorption on the adhesive damage in bonded composite repair of aircraft structures. The damage zone theory was implemented in the finite element code in order to achieve this objective. In addition, the effect of the water absorption, by the adhesive, on the repair efficiency was analyzed by computing the stress intensity factor at the crack tip. The obtained results show that, when the water absorption increases the adhesive loses its rigidity, which reduces the repair durability. Besides, it leads to the increase of the stress intensity factor at the crack tip indicating a reduction in the repair efficiency.