Introduction To Composite Material

Published Date: 02 Nov 2017

Composites are used by us almost every day; if we take a look around they are almost everywhere and have been around since the beginning of the human civilization when people used to make bricks from mud reinforced with straw. Some present day examples for use of composite materials are tennis racket, golf clubs, cars and planes.

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Composite are often a combination of at least two materials with distinct properties; many composite are made up of just two material, one that acts like a glue to surround and bind and other reinforce fibres.

Now a days engineer prefers composite material instead of steel because composite materials are generally stronger, lighter and much more resistant to extreme temperature. Aeronautics industries are using composite material for aircraft parts that are tougher and more efficient than conventional parts. The critical goal of the aeronautics/space industry for using composite material is ‘The reduction of weight combined with strength’ or ‘the reduction of weight and saving precious fuel’.

We can find composite in nature as well; a tree is a very good example which is made from long cellulose fibres (polymer) bind by lignin which is weaker. Our human bone is also a composition of different material which is called hydroxyapatite and soft flexible material called collagen.

Use of composite in Aerospace/nautical industry

Aeronautical/space engineering is developing very fast. The first composites were introduced around 1940s called polymer matrix composite. As usually the airplanes have been made out of metal especially alloys like aluminium now however engineers are working with carbon fibre composites which was introduced around early 70s.

This is Boeing 787 the first commercial jet transport to be manufactured out of composite materials.Material used in the Boeing 787

As we can see on the figure above 50% of the materials that are used on an aircraft is composite and others are steel, aluminium and others. Composite also have other advantage beside the weight reduction they are the structural composite can integrate an acoustic damping system, thermal transfer characteristics and electric function. Composite also reduce the amount of fasteners used. So we could say composite has a major role at present day aerospace industry.

Compiste materails used in Jet engine

In 1903 when the wright brothers first build an aircraft, the material used have been evolving continuously and improved a lot to a present day. When the two brothers handcrafted the very first propeller for the airplane they were able to achieve 68lbs of thrust each, today however the fan blade on GE90 made of composite are capable of producing 127,900lbs of thrust almost 2000 times the power they (wright brother) created.

Composite material used in jet engine is carbon fiber-reinforced polymer which is used in parts like engine case and fan blade. Composite jet engine case is 30% lighter than metal fan case and strong enough to released titanium blade.

What exactly is carbon fiber?

Carbon fiber is a composite material which is made out of complex design of rigid fiber stands that are bathe in epoxy resin giving out surprising characteristics. In each strands there are about 3000 -12000 carbon fiber all packed together to the form of yarn. C:\Users\12014087\Desktop\carbon-fiber-weave.jpgC:\Users\12014087\Desktop\CF-vs-Hair1.jpg

Carbon fiber reinforced composite material is used in different industry where the light weight and high strength are needed. Bicycle frame, racing car, spacecraft parts, fishing rod are the common examples of use of carbon fiber.

Composite are have been used in the outer parts of the modern jet engine. These include nacelles, fan exit guide vane, ducts etc.

The main parts where the composite are used in the jet engine are:-

Blades

Case C:\Users\user\Desktop\figure-1.jpg

Talking about the composite material which is used in jet engine such as GEnx is carbon fibres; which is light and work on the key to reduce weight, saving fuel. Companies like GE and others are investing millions on composite material carbon fibre and ceramics which is a lot durable and weigh a third less than those made with the usual nickel and titanium alloys.

This new technology is a superior product that gives the airline customers acquires more fuel efficient and extremely durable fan blade. According to the new inspection done the fan blade has flown approximately 28 million miles, which is a equivalent to 117 trips to the moon or 6 and half years on the air.

Above is the chart of the different metal and composites that shows the strength/density. As we can see carbon fiber reinforced polymers have a highest strength/density.

Characteristics of composite materials are:

High specific strength and modulus, as well as high fatigue strength and fatigue damage tolerance

Corrosion resistance and durable

Production of both material and structure or component in a single operation manufacturing flexible, net-shape, complex geometry

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