Aircraft engineers are looking at engineering plastics
to reduce the dry weight of aircraft without sacrificing
physical performance of the metal parts they are replacing.
They require lightweight materials that provide processing
flexibility, reduce manufacturing costs, and provide
durability in harsh environments. Engineering plastics and
composites have successfully displaced metals in a growing
number of aerospace applications because they are
exceptionally strong, inert, and inherently flame retardant,
and can be easily fabricated into tight tolerance parts.
In addition to standard stock shapes of engineering
plastics, aerospace components can also be manufactured using
a matrix for thermoplastic composite prepregs made of carbon,
glass or aramid continuous fibres. Its outstanding properties
make it an excellent substitute for metals and thermoset
composites. Composite materials can provide a much better
strength-to-weight ratio than metals: sometimes by as much as
20% better. The lower weight results in lower fuel
consumption and emissions and, because plastic structures
need fewer riveted joints, enhanced aerodynamic efficiencies
and lower manufacturing costs.
Carbon fibre reinforced plastic (CFRP) derives its high
structural performance from the prodigious strength of the
individual strands of carbon. By way of comparison, the
ultimate strength of aerospace grade aluminium alloys is
typically 450MPa whilst that of a carbon fibre would be five
times that value. As carbon composites are, additionally,
only 60% of the density of aluminium, the potential for
weight reduction in an airframe application is also apparent.
In addition to strength and weight, fibrous composites are
thought to be virtually immune from ‘fatigue’.