Composites

An IHS White Paper

Composites in Aerospace Applications
By Adam Quilter, Head of Strength Analysis Group, ESDU International (an IHS company)
Except in very special cases, the laminate will still be

Introduction
The aerospace industry and manufacturers’ unrelenting passion to enhance the performance of commercial and military aircraft is constantly driving the development of improved areone such class of materials that play a significant role in current and future aerospace components. Composite applications because of their exceptional strength and

anisotropic, but the variation in properties with respect to this approach is taken a stage further and the differently

direction will be less extreme. In most aerospace applications,

high performance structural materials.Composite materials

oriented layers (anything from a very few to several hundred in number) are stacked in a specific sequence to tailor the properties of the laminate to best withstand the loads to

materials are particularly attractive to aviation and aerospace stiffness-to-density ratios and superior physical properties. A composite material typically consists of relatively strong,

whichit will be subjected. This way, material, and therefore in the aviation and aerospace industry.

weight, can be saved, which is a factor of prime importance

ESDU International (www.esdu.com)
provides validated engineering design data, methods and software for the engineer. 1,340 design guides with

Another advantage of composite materials is that, generally speaking, they can be formedinto more complex shapes number of parts making up a given component, but also than their metallic counterparts. This not only reduces the reduces the need for fasteners and joints, the advantages of

stiff fibres in a tough resin matrix. Wood and bone are natural composite materials: wood consists of cellulose fibres in a in a collagen matrix. Better known man-made composite carbon- andglass-fibre-reinforced plastic (CFRP and GFRP materials, used in the aerospace and other industries, are lignin matrix and bone consists of hydroxyapatite particles

These are presented in over supporting software and are the result of more than 60 years experience of providing data and techniques for engineers with information,

which are twofold: fasteners and joints may be the weak points of acomponent — a bolt needs a hole which is a site, and fewer fasteners and joints can mean a shorter assembly time.

respectively) which consist of carbon and glass fibres, both

stress concentration and therefore a potential crack-initiation

of which are stiff and strong (for their density), but brittle, in nor strong. Very simplistically, by combining materials with with most or all of thebenefits (high strength, stiffness, the weaknesses of the individual component materials.

fundamental design and sional Institutions, ESDU

a polymer matrix, which is tough but neither particularly stiff

analysis. Endorsed by profesdata and software form an operation of companies the world.

complementary properties in this way, a composite material toughness and low density) is obtained withfew or none of

the greater time likely to be needed to fabricate the compothe individual layers, which are often pre-impregnated nent in the first place. To produce a composite component, (‘pre-preg’) with the resin matrix, are cut to their required shapes, which are all likely to be different to a greater or lesser extent, and then stacked in the specified sequence to keep the uncured layersin the required shape prior to, and during, the curing process). This assembly is then

Shorter assembly times, however, need to be offset against

important part of the design large and small throughout

CFRP and GFRP are fibrous composite materials; another Metal matrix composites (MMC) that are currently being

category of composite materials is particulate composites. developed for...