The strength recovery effect of scarf bonding on the CFRP laminates with impact damage

Impact damage can affect the carrying capacity and service life of aerospace composite structures seriously. In this study, the carbon fiber/epoxy composite (ZT7H/EC3448) was used for scarf bonding repair for CFRP (Z7TH/QY9611) laminates to restore strength. In view of the impact sensitivity of bonding repair of CFRP laminates, a three-dimensional (3D) finite element model (FEM) of the whole damaged response from impact to compression-after-impact (CAI) was established by the subroutine of ABAQUS finite element simulation software. Combined with the experiments of low-velocity impact and compression, the impact damage mode and CAI response of the intact laminates and the wet bonding repaired laminates were evaluated by analyzing the impact response, the failure situation and the residual strength. The results show that the damage of both started in the impacted area and expanded to complete failure in the direction of the vertical fiber. Unlike the intact laminates, the patch of the repaired laminates absorbed a lot of impact energy, which greatly reduced the damage to the original laminates, and the CAI performance for the wet bonding repaired laminates by ZT7H/EC3448 recovered to 97.7% of the intact one.