Composites of natural origin have been used since the beginnings of aeronautics because of their light weight. Currently, the use of organic matrix composites results from the constant concern for fuel economy, and therefore fossil energy.
Nevertheless, lightness cannot be achieved at the expense of other properties. Mechanically, the ratio between properties and specific mass makes it possible to compare materials, and this comparison is favourable to composites. Shock resistance (birds) and electrical properties (lightning) are other properties to be optimized for structural materials, particularly for polymer-carbon composites.
The use of composite materials is general in secondary parts (leading edges, flaps,...) and it extends to primary structural parts such as the fuselage. Even for engines, manufacturers are now turning to organic matrix composites (including thermoplastics) for parts that are not subjected to too high temperatures.
Composites processing techniques are generally pressure and/or high temperature (compression, (SQ)RTM, ATL, AFP, etc.) techniques for thermosetting resins, and injection for thermoplastics. For the future, nanocomposites and multifunctional hybrid materials open up new perspectives.
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