Composites for high-temperature applications
Vacuum-assisted resin infusion moulding is a manufacturing process used to produce high-quality, large-scale components. In this process, preform fabrics are placed in a one-sided mould and a plastic vacuum bag is added on top. The open mould is connected with a resin source and a vacuum pump. Liquid resin infuses into the reinforced fibres thanks to the vacuum. A thermosetting resin – cyanate ester – and a woven twill fabric were used within the EU-funded project LRI-HIT (Investigations of liquid resin impregnation and out-of-autoclave curing of composites for the high temperature aerospace applications). Both resin and fabric were selected from the pool of aerospace-qualified materials to manufacture a sample structure resembling section 19 of an aircraft. A number of parameters were reviewed before making the final choice. Among these factors were the resin viscosity and inlet geometry that may affect the cyanate ester's flow and, hence, quality of the demonstration product. Curing and de-moulding steps followed the resin impregnation process to finish the particular portion of the aircraft fuselage. Partners' research focused on meeting the need for lower-cost out-of-autoclave composite moulding. To achieve this aim, the Quickstep proprietary manufacturing process was further developed. A more balanced pressure during the heated mould process promises reduced cure cycle times as well as increased strength and improved appearance. The resin infusion process is a cost-effective method of manufacturing high-quality composite parts that are difficult or prohibitively expensive to make by any other method. The new LRI-HIT technology can be used to fabricate large composite parts to aerospace standards. The added flexibility to co-cure and meld components allows production of structurally complex parts. LRI-HIT has provided manufacturers with increased design flexibility and reduced processing costs, helping to maintain Europe's competitive edge in the aerospace industry.
Keywords
Composite materials, aircraft, vacuum-assisted resin infusion, liquid resin, aerospace applications, cyanate ester
