Effect of relative impact location and patch layer number on impact resistance of adhesive repaired CFRP composite laminates

In this paper, based on continuous damage mechanics and cohesive element model, the internal and interlaminar damage of carbon fiber reinforced polymer (CFRP) composite laminates with different impact locations and patch layers under low velocity impact load were numerically analyzed in ABAQUS, and the results were compared with the experimental results. Five kinds of repaired structures corresponding to the relative impact location of 0 mm, 10 mm, 20 mm, 30 mm and 40 mm were selected. The impact force and impact energy of the repaired structure during the low velocity impact were obtained from numerical and experimental approach. By keeping the monolayer thickness unchanged, the layer number of the used patches increased from 1 layer to 5 layers, and the low velocity impact response of repaired structures was obtained numerically and experimentally. The results show that when the impactor contacts repaired structures, it causes damage to the patch, but the patch definitely improves the impact resistance of the damaged parent laminates. When the impact point is closer to the damage hole of the repaired structure, the more serious the damage of the structure is caused by the impact. Moreover, the increase of the layer number within the patch design improves the impact resistance of the repaired structure. An optimum layer number is 2 obtained by optimizing the layer number, and the corresponding delamination area is reduced by 19.9% compared with damaged parent laminate without repair.