In
IN ACTION 45
Cycling to victory with composites
materials. The frames of these hi-tech bicycles are made of glass / carbon-epoxy composites. This leads to a 30 per cent red uction in weight with the added ad vantage that the frames are eight per cent stronger than conventional alloys. The composite cycles have more than proved their worth. Greg Lemond, three-time winner of the Tour de France, the world's
46 HARDY COMPOSITES
most exacting and exciting bicycle race, used a composite f+am-€-bic-y:~in 1990 to pedal his way to his third victory.
Lightweight yet sturdy
Not far behind the bicycle ind ustry in using com posi tes are the motorcycle manufacturers. Heron Suzuki in collaboration with Ciba-Geigy Bonded Structures have designed and built
IN ACTION 47
Heron Suzuki motorcycle
a 500 cc motorcycle with a carbon fibre composite chassis.
It has a high stiff- ness to weight ratio which is a hallmark of composites. This eliminates many problems pre-
'viously en-
countered with steel frame racers.
It also shows remarkable resis- tance to damage.
An earlier model
emerged un-
scathed in a multi
cartwheel crash at 225krn per hour. The chassis is at present undergoing further assessment and evaluation at the Suzuki Motor Company in Japan.
Motoforms of Brussieu, France, one of the very few European companies specializing in making motorcycles for major rallies, now uses composites too. The shell of the Motoforms motorcycles is a composite structure weighing only 6 kg. The parts are made from glass fibres like Lyvetex and Kelvar laid up with an Araldite matrix system. The entire motorcycle weighs only 130 kg, but is super tough and efficient. It took the battering and vibrations of a 13,000krn rally over a tough African terrain without cracking under stress. Motorcycles thus modified by Motoforms have won laurels at the Rally des Pharaons in Egypt and Rallye del' Atlas in Morocco.
Glass fibre-polyester or epoxy composites are the usual materials for the prod uction of automobiles and caravans and commercial vehicles. In India, the bodies of Dolphin, Mon-
48 HARDY COMPOSITES
Mikki, Eddy Electric and Miracle
IN ACTION 49
GTP ZXTurbo
tana and Sipani Dl cars are made of glass fibre reinforced plastics. Even though most Indian cars have metal bodies, entrepreneurs planning to introduce new cars are opting for fibre glass. Mikki, Edd YElectric and Miracle, three low priced cars slated to hit the Indian roads in the near future, would have fibre glass bodies.
In many European countries, the bodies of cars, trucks and buses are made of composite materials. For racing cars too, composites are often the material of choice. Tankers used for transporting milk, fruit juices, wbe or chemical products are also made of glass fibre reinforced plastics. Hummel, a high mobile multipurpose vehicle is the successor to the jeep. It has hoods, grill, doors and battery made of fibre reinforced plas- tics.
50 HARDY COMPOSITES
Passenger cars are also being incorporated with com- posites parts. Fibre reinforced epoxy composite shafts are used in automobiles because they are efficient and have a simple construction design as compared to conventional materials. They also have better noise and vibration control.
High speed rally cars have extremely demanding require- ments, which have" to be D}et in totality for. commef.1q.a1:M performance on the track. An Aralditematrix resin has Been chosen by Ford and Hamble Composite Systems of UK to prod uce the aramid / epbxy rear end for a new rally car named RS 200. In 1989, the NissanGTP Turbo came first in nine out of 15 events. The GTP ZX Turbo owes at least part of its performance to the advanced composites used to make its outer shell and some inner parts as well which reduced its overall weight by about 30 per cent. In 1991, a two- seater prototype with new technology and low-drag design was tested. This car, a Ren:mlt Laguna, can accelerate from zero to 100 km per hour in only six seconds and then reach a top speed of 250 km per hour. It also has a lightweight, corrosion resistant carbon fibre-Araldi te matrix composite bod y. G and V.Duqueine, the car manufacturers, specialize in the design
Renault Laguna
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Composite belts enhance safety in tankers
and fabrication of composite structures and for several years had built all- composite shells for Formula 3 and Formula 3000 cars.
Composite materials are also used to enhance safety in tankers carrying hazardous chemicals. AluminiuIlf tanks have to be reinforced to minimize the risk of damage and leakage in the event of accidents. The conventional response would be to increase wall thickness by welding an extra aluminium sheet on a tank. However, a continuous weld
52 HARDY COMPOSITES
extending the entire length of the tanks could significantly modify the properties of the original structure. The welding operation itself could raise serious explosion hazards in old tanks . .High performance composite materials were, there- fore, pressed into service. Ararnid fibre fabrics laid wet with Araldite were used as a belt, which reinforced both the sides and the ends of tank. This cost effective method has been in use since 1988 and ensures crash safety of thousands of German tankers.
Even railways are being transformed by composites. The British Railways Board has designed a high speed train with reinforced plastic foam body. Composites Aquitaine, a firm that specializes in composite structures has built coaches with glass phenolic parts for Taiwan's Metro.
Light Canard Research Aircraft (LCRA)
IN ACTION 53
Advanced Light Helicopter (ALH)
The aircraft industry has always been interested in the use of composites. In jet liners, a reduction of a single kilogram in weight can mean $ 2000 in life time fuel economy for an aircraft. So, it is only natural that aircraft manufacturers have started using composites in jet engines.
India has not lagged behind in using composites for aircrafts. In 1986, the National Aeronautical Laboratory, Ban- galore, successfully test flew the first Indian aircraft to be made entirely out of composite materials instead of conven- tional aluminium alloys. This all-composite Light Canard Research Aircraft (LCRA) was made entirely out of rigid foam and fibre-glass composites. The technology used in making the LCRA is similar to that used by Rutan Aircraft in USA for making the Voyager, which created aviation history by flying
54 HARDY COMPOSITES
non-stop around the world. Not only are major components being made of composiotes but smaller parts like piston rings are also being replaced by composites. This has resulted in reduced engine wear and tear, and led to low maintenance costs. The share of composite parts and structures in air crafts is expected to touch 55 per cent soon.
Carbon-carbon composites are well suited for aircraft brakes. These cost roughly twice as much as the conventional metal brakes, but are economical because of the weight saving they provide. These brakes also require less maintenance in terms of landings per overhaul. The first airliner to use car- bon-carbon composites was Concorde, but now almost all military as well as civil aircrafts use this type of composites.
Replacement of metals by polymer composites in helicop- ters has resulted in a more readily assembled unit with 9000 fewer components, weight reduction and improved reliability. The amphibious vehicle Sea Wind, which can 'land' on water as well as fly was made from reinforced vinyl ester resin. The Advanced Light Helicopter (ALH), the first prototype of which has been designed and developed by the Hindustan Aeronautics Ltd. is no exception. The singular feature of this helicopter is the extensive use of fibre com- posites. Fibre reinforced composites include glass, carbon or Kevlar in a matrix of epoxy resin. About 60 per cent of the helicopter's surface is made up of composites. Hindustan Aeronautics Ltd. is the first to use composites for stress bearing structures such as the four-bladed tail rotor. The four-bladed hingeless main motor also comes with a com- posite hub.
Wide use of composites has drastically cut down the weight of an ALH. It weights just 2,500 kg. This apart, the use of composites instead of the -conventional metallic alloys makes an ALH difficult to detect by radar. This will be of advantage during war. This Indian helicopter prototype is also designed to perform equally well during peacetime when it would transport cargo, perform coast guard duties
IN ACTION 55
and rescue operations. It could be pressed into, emerg~ncy medical services too. It was successfully test-flown' by Capt.
Baljit Singh Chhoker on 31 August, 1992.
ULM C with composite fuselage
The Super Puma AS 332 MK 2 helicopter is built by Aerospatiale. This leading European manufacture has achieved a 20 per cent weight reduction by using composites instead of light alloys. Another ultralight aircraft that can even function as a glider when required is the ULM C.
Manufactured in France for maintaining surveillance on forests, and oil and gas pipelines, it uses composites for its fuselage.
Metal fatigue is a thorn in the flesh of the aviation industry.
It is the failure caused by decay of mechanical properties of metallic parts due to repeated stress on them. Metal fatigue can and do lead to disasters. However, the problem can be solved by using a novel composite material comprising a laminar or sheet-like combination of aluminium and ad- vanced glass/epoxy composite. This new composite is
56 HARDY COMPOSITES
marketed under the generic name Aerospace ARALL. A glass fibre reinforced variety of Aerospace ARALL has been intro-
Metal fatigue-no longer a problem
duced. It is called GLARE. It has extraordinary resistance to fatigue and do not allow microcracks to propagate and lead to bigger ones. GLARE is also very light and could save 25-30 per cent of fuselage weight in an aircraft. It is a cost effective replacement for aluminium. And since it is resistant to fatigue, it means a further cost reduction due to longer life and less frequent inspection.
Even spacecrafts use com posites. There are many instances of the use of glass reinforced laminate construction in manned space vehicles. Glass was chosen to provide heat insulation as well as to minimize weight. The Apollo boost protective cover used glass composites. Food containers, equipment protective covers, numerous clips and brackets in
IN ACfION 57
the Apollo command module were fabricated from glass- cloth reinforced polyimide-Iaminate materials. Heat shields, designed to protect the spacecraft from the heat generated by friction as it moves through air, were made from glass-cloth reinforced by phenolic resin.
Saturn S-11 composite applications
The module transporting astronauts from lunar orbit to the surface of the moon and back had glass filament reinforced silicone laminates in the crew compartment ceilings, side panels and electrical covers. The ladder used by the astronauts to descend from the craft on to the lunar surface was also made of composites. Glass fibre reinforced com- posites have been used in Saturn S-II booster used to launch Apolio vehicles.
Boron epoxy composites have been used in Pioneer 10 spacecraft. Space shuttle orbiters use a variety of composites.
58 HARDY COMPOSITES
. Outenegment l.magnetometer boom
Pioneer 10 spacecraft composite applications
Orbiters use boron-epoxy, graphite-epoxy, boron-polyimide, graphite-polyimide, boron-aluminium and Kevlar-epoxy composites to name but a few.
The area where the use of composites has rewritten the rules of nature is the field of biomedical implants. The loss of a limb now no longer has the same crippling implications as it once did. Fitted with life-like composite limbs, amputees can not only lead normal lives but also participate in strenuous pastimes like bicycling, squash and skiing.
Endolite, mainly a carbon-fibre composite system, is a high- technology prosthesis. It is an advanced lightweight system with ingenious knee, ankle and foot designs. Ther-
IN ACTION 59
Near normal life with composite prosthesis
moformed polyethylene and polyurethane foam are used to simulate flesh, which is covered with life-like silicone skin.
Made by aBritish firm, Endolite composite prosthesis allows amputees to lead normal lives. At present about 65 per cent of the British amputees use the Endolite system. USA and Germany are also large scale users of this composite system.
India too is experimenting wi th cornposites in the biomedi- cal field. Composite calipers or braces have been jointly developed for the first time in India by the Department of
60 HARDY COMPOSITES
Aerospace Engineering, Indian Institute of Technology, Bom- bay and the SDM Hospital, Jaipur. The calipers are made of thermosetting plastic materialneinforced by carbon or glass fibre as well as pure polypropylene material. They are lighter and more comfortable to wear as the materials can be moulded to suit the contours of the human body. Clinical trials carried out on over 1,000 patients have confirmed their better acceptability and superiority over conventional calipers made of metal and leather, which are heavy and cumbersome.
Biomaterial composites utilising bioceramics include bioceramic coatings on metals and polymers and combina- tion of surface active glass ceramics and polylactic acid with metal, carbon or calcium/ phosphorus based glass fibres.
Isotropic carbons produced at low temperatures have excep- tional wear and fatigue properties associated wtih biocom- patibilityand hence are best suited for clinical applications.
Other fields where composites are also being used are electrical and nuclear industries. In the electrical industry, composites are increasingly being used in incandescent and fluorescent lamps. In the r.uclear industry, composites based on resin materials are used in equipment for radiation monitoring, radiation protection, high vacuum apparatus, control rods and cladding materials to name but a few. The use of composites is by no means restricted to only these industries. At work or at play the versatile composites have carved out their own niche and in doing so have greatly enriched the quality of modern life.