SECTION TITLE COMPOSITES
The Airbus 350 incorporates at least 50% composite structure by weight
FIGURING OUT FIBRES C
Matt Dawson discusses what engineers need to consider when choosing the right composite fibre types and properties
omposite materials offer a blend of properties that set them apart from traditional engineering materials. Characteristics such as high strength,
light weight, and ease of forming mean that engineers prefer composites for a wide variety of uses. Indeed, there are applications that would be impossible without them. Once the decision to consider composites has been taken, one of the first questions to be addressed is that of
The leisure marine sector makes extensive use of glass fibre
fibre selection: Laminate performance depends strongly on the fibre properties, so it is worth investing effort into making the right choice. Tere are many fibre types from which to select, ranging from low-cost to highly exotic and offering a correspondingly wide range of properties. Understandably, the number of options can be a little daunting, so this article will introduce the more commonly available types of fibre, their properties, applications, and pros and cons.
CARBON FIBRES Carbon fibres offer outstanding specific strength and stiffness, making them ideal for high-performance applications such as aerospace and motorsport. Even in the risk-averse commercial aviation sector, carbon fibre composites are now supplanting aluminium alloys in airframe construction – new aircraft such as the Airbus A350 and Boeing 787 incorporate at least 50% composite structure by weight. Carbon fibres also offer excellent fatigue performance, environmental resistance and thermal stability. Teir density is in the range of 1700-1900kg/m3
.
Carbon fibres consist of graphene planes orientated parallel to the fibre direction. Tey are manufactured from either PolyAcryloNitrile (PAN) or mesophase pitch precursors and are available in a variety of grades, each offering a different balance of strength, stiffness and cost. Despite their advantages, there are
reasons why carbon fibres might not be the right choice: the most obvious being cost. If low weight isn’t critical, the use of carbon fibres may not be justified. It is also true that carbon fibre manufacture is an energy- intensive process, with corresponding implications for CO2
emissions. In some
cases however, such as aviation, fuel savings resulting from a lighter structure will more than offset the emissions embodied in the
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