Repair of impact-damaged carbon fiber PEEK composites

The possibility of repairing impact-damaged carbon fiber PEEK composites has been assessed. Multidirectional (0°,90°,±45°)_2s laminates were subjected to low velocity impact loading in order to create varying degrees of visible and non-visible damage. The level of damage incurred was evaluated using the C-scan technique and by removing and polishing sections adjacent to the point of impact. Many of the damaged specimens were 'repaired' by placing them in a press and heating according to the manufacturer's recommended procedures for molding carbon fiber PEEK. The success of the repair was then assessed by undertaking tension, compression and flexure tests on the specimens and comparing the results with the strengths of the unrepaired specimens. The experimental results indicate that delamination-type fracture such as that incurred at low incident energies can be fully repaired without any loss in mechanical integrity. Extensive fiber fracture was incurred at energies of 12J and above. Here, the success of the repair was not total but the residual compressive and flexural strengths of the repaired specimens were still considerably greater than those of the as-impacted specimens. Limited tension testing suggested that thermal repair of heavily damaged components can have a negative effect on their load-bearing ability.