An Experimental Study on the Low Velocity Impact Response of Repaired Carbon Fibre/Benzoxazine Composites

As structure materials, carbon fibre/benzoxazine (CF/BZ) composites are prone to damage, which compromises their structural performance significantly. Scarf repair is an effective means of restoring structure performance. In this paper, one side scarf repair CF/BZ (OR-CF/BZ) and both sides scarf repair CF/BZ (BR-CF/BZ) were prepared to investigate the influence of repair geometry on low velocity impact response of adhesively bonded scarf repair in damaged CF/BZ laminates. The intent of prepare BR-CF/BZ is to reduce the repair area. The CF/BZ laminates are removed the damage area with a rectangle cutout from one side and two sides respectively and repaired with scarf patches. Low velocity impact with different impact energy levels are performed to investigate the impact performance of repaired composites. Visual and CScan inspection are conducted, in order to observe the extent of the damage in the repaired composites. Compression after impact (CAI) are undertaken to measure their residual strength. Micro-graphs of the specimen's cross-section are also produced in an effort to observe the fractured sections and characterized the various fracture mechanisms involved. Results show that the damage areas after impact of BR-CF/BZ is larger than that of OR-CF/BZ and CF/BZ. The penetrating damage of CF/BZ, OR-CF/BZ and BR-CF/BZ occur at 40 J, 50 J and 60 J impact energy respectively. The CAI strength of BR-CF/ BZ is higher than that of OR-CF/BZ and CF/BZ. While the CAI modulus does not change greatly. The failure mechanism includes impact damage failure and growth of compressive failure during CAI test. The impact point is the most seriously damaged zone of the CAI specimens.