In-field repair of composite air craft is often performed in difficult conditions and hence needs to be as simple as possible. Current repair techniques generally involve the application of composite patches based on thermosetting epoxy resin via either wet lay-up, prepreg stacking over a film adhesive, or bonding precured patches. These methods of repair are very effective, but a complex cure cycle under controlled conditions is required and the use of epoxy resin means that storage must be taken into consideration. Composite patches based on thermoplastic resins overcome both of these problems; they do not require curing, and have no special storage neeeds. Thermoplastics can also be thermoformed and can hence be produced in sheet form and formed to the correct shape in situ during adhesive bonding to the surface to be patched, using vacuum and heat. With its low thermoforming temperature and good mechanical properties, polycarbonate is a goood candidate for use as a thermoplastic matrix, with woven carbon fibre fabric as the reinforcement to produce patch laminates. The present paper describes the use of solution impregnation together with film stacking to produce patches of acceptable quality and how these patches were formed without any wrinkling using double diaphragm forming. It was shown that thermofoming of polycarbonate based laminates can be performed at lower temperatures than those previously reported, with forming beginning between 140 and 150 deg C when a heater mat and vacuum bag were used. To avoid wrinkles double diaphragm forming was used as an effective method to produce well formed polycarbonate/ carbon fibre laminates.
Fabrication of woven carbon fibre/polycarbonate repair patches
Herstellung von Ausbesserungsfpflastern aus gewebten Carbonfasern in Polycarbonat
Composites, Part A: Applied Science and Manufacturing ; 27A , 11 ; 1089-1095
1996
7 Seiten, 5 Bilder, 7 Quellen
Article (Journal)
English
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