In addition of binding the patch to the cracked material, adhesives play an important role in bonded composite repair because they make the bridge of transfer of loads between the patch and the cracked material. Indeed, any damage in adhesives will affect the efficiency and the performance of the repaired structure by composite patches.In this paper, two different adhesive shapes were numerically investigated, using finite element method in order to estimate the damage zone area on the adhesive bonded composite repair in 5083 marine grade aluminum alloy and its effect on the efficiency and performance of the repaired structure. The obtained results proved that the circular shape causes less damage than the rectangular one for the three crack lengths chosen. Moreover, both shapes of adhesive maintain their performance repair without disband risk and without reaching the critical value defined by Ban and co-authors (Dr=0.2474). Furthermore, it is concluded that the damage zone increases with the increase of the adhesive thickness and the decrease of the patch thickness and the use of circular shape is more effective than the rectangular one for the configurations and loading conditions studied.

In bonded composite repair of aircraft structures, the damage of the adhesive can thus reduce significantly the efficiency and the durability of the bonded composite repair. The adhesive damage models using critical zone have proven their effectiveness due to simplicity and applicability of the damage criteria in these models. The scope of this study is to analyze the effects of the patch thickness and the adhesive thickness on the damage damage in bonded composite repair of aircraft structures by using modified damage zone theory. The obtained results show that, when the thickness of adhesive increases the damage zone increases and the adhesive loses its rigidity, inversely when the patch is reduced the adhesive damage becomes more significant.

In this paper, the simultaneous effect of corrosion and cracking on the performance of the bonded composite patch repair in aluminum alloy A5083 marine structure was investigated using three-dimensional finite element methods. To this end, two patches made of carbon/epoxy and boron/epoxy, bonded on corroded plates with and without crack, were tested under different applied loads. The effect of both corroded and cracked materials on the damage of the adhesive FM73 was also highlighted. The obtained results show that the corrosion has a significant effect on the quality of the repair performance. Indeed, it is proved that, the rate of damage increases with the increase of the applied load and is more significant in the case of plates cracked and repaired by carbon/epoxy patch compared to that of boron/epoxy patches.

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