NDI OF IMPACT DAMAGED COMPOSITE PANELS

The service life of a composite component can be drastically reduced as a result of impact damage due to a bird strike or foreign object damage. It is well documented that the external surface may show no damage and yet degradation in the form of delamination or cracking may occur internally. In order to assess composite materials' resistance to impact damage, various test panels were manufactured in a range of fibre/resin combinations. This paper describes the non-destructive inspection of various thermoplastic composite material systems which had been impacted by simulated bird strikes. Basic ultrasonic 'C' scans were performed to evaluate the extent of the area of the damage and further 'B' scan data was gathered using a semi-automated contact unit for through thickness evaluation. Standard NDI equipment and techniques were utilised as opposed to more advanced methods (ie polar backscatter) in an attempt to duplicate current shop-floor inspection capabilities. The results presented here are part of a larger program aimed at developing a comprehensive procedure for the design of impact resistant composite structures.