Use of composite materials in Aerospace
Composite materials have been used in aerospace in applications such as engine blades, brackets, interiors, nacelles, propellers/rotors, single aisle wings, wide body wings.
Although the volumes of fibre reinforced polymer composites (FRPs) used for aircraft applications is a relatively small percentage of total use, the materials often find their most sophisticated applications in this industry. In aerospace the performance criteria placed upon materials can be far greater than in other areas – key aspects are light-weight, high-strength, high-stiffness and good fatigue resistance. Composites were first used by the military before the technology was applied to commercial planes. The first military applications were in radomes and then in secondary structures and internal components. The modulus of glass, however, is low compared with that of metals and so it was not until the introduction of carbon reinforcements that primary composite structures were developed. Nowadays, composites are widely used and this has been the result of a gradual direct substitution of metal components followed by the development of integrated composite designs as confidence in FRPs has increased.
The Airbus 320 uses a range of components made from composites, including the fin and tailplane. This has allowed a weight-saving of 800 kg over its equivalent in aluminium alloy. Composite materials comprise more than 20% of the A380's airframe. Carbon-fibre reinforced polymer and glass-fibre reinforced are used extensively in wings, fuselage sections (such as the undercarriage and rear end of fuselage), tail surfaces, and doors.
Other examples include: Airbus Industries A320 and A380 , Harrier AV-8B, European Fighter Aircraft (EFA), Aircraft propellers, Helicopter Airframes , Helicopter rotor blades and Helicopter rotor hubs. A good case study of the Boeing 787, which is 50% advanced composite materials can be found: http://www.boeing.com/commercial/aeromagazine/articles/qtr_4_06/article_04_2.html
The successful application of composites in missiles has led to the development of primary structures for space vehicles. In fact, space applications lend themselves in many ways to the utilisation of new materials. For satellites, for example, the timescales from concept to manufacture can be as little as two years and the short product runs normally involved, the materials element in the final cost is often relatively low. Also in many applications no other material is suitable for technical reasons.
Once in orbit, mechanical loads are comparatively low. Environmental conditions can be extreme and severe thermal cycling can occur, as well as the effects of high-vacuum and erosion through atomic oxygen or micrometeroid impacts. Glass-fibre composite (GRP) is used in applications where thermal insulation is important, for example in local bracketry. The material is also used in some antenna reflectors.
Carbon-fibre composite (CFRP), however, is most often associated with space applications. The potential for very high-stiffness and excellent thermal stability over a wide temperature range make CFRPs ideal. Examples of their application include: fairings, manipulator arms, antennae reflectors, solar array panels and optical platforms and benches. They have also recently been used for primary structure applications. In the past the need for a combination of stiffness and strength, and for thermal and electrical conductivity have favoured metals. However, the constant pressure for weight reduction means that now some satellites have been built with a predominantly composite structure sub-system.