At the present time, space and aerospace
textiles are making a significant contribution to the increasing market for
textiles, assert M V Ragavendra Pavan, Karthik Macharla and Dr J
The history of textiles can be traced
back to the age when human beings tried to cover their body for safety and
protection - even well before the production of fabrics and other products
started on machines. Today applications of textiles have crossed many
barriers beyond the regular use which man never expected. One such area is
space and aerospace. The design, manufacture and applications of textile
composites in space and aerospace has become one of the most predominant
aspects in present-day textiles.
The applications of these composites in
space suits for launch and space walks require zero defect performance. They
are made from PBI non-flammable high performance fibres, which require air
purifying, cooling and pressurising systems, so that the suit should be
thermal resistant and thermal insulated.
High specific modulus and high specific
strength are the most desired characteristics of materials in aerospace
structural applications. They should have good fatigue, stress resistant,
better dimensional stability and conformability, which help in improving the
fuel economy of the aircrafts. Carbon, Kevlar, Boron nitride fibres, etc,
are used as composite reinforcements in making wings and other body parts
for a variety of commercial and military aircrafts.
Today, the world advances in aerospace
textiles by the use of composite materials based on ultra strong Aramid
fibres, which have low density, high specific strength combined with
attractive specific modulus. Fabricating of composite structures with these
Aramid fibres will resist flame, high temperatures, organic solvents and
lubricants. In addition, all these fibres are pliable and can easily be
woven by conventional methods.
When astronauts travel through space,
they face complex environment. Earth's gravitational attraction holds
atmosphere comprising a mixture of gases like nitrogen, oxygen, carbon
dioxide and thick form of water vapour. This atmosphere protects us from
various factors. When the astronauts leave the surface of earth and travel
into the space, they must be ready to meet the environment available there.
There are numerous health risks caused
by the harmful radiations, when the astronauts are exposed to them. Some of
the short-term effects and
recoverable effects like nausea and long-term
effects like cataract, cancer and damage to the central nervous system or
even death are caused when exposed to these radiations over a period of
time. Hence, there is a need for a system to determine, detect and prevent
certain level of radiations, pressures and temperatures encountered by the
astronauts to keep him alive in that environment. Such a system is a space
suit. A space suit is a complex system of equipment, specially designed to
protect and keep a person comfortable in the rough environment of outer
space. This applies to the Extra Vehicular Activity (EVA) outside the
spacecraft and is applied for walking on the moon.
The space suit must possess the
1. Lighter in weight.
2. Flexible in handling.
3. Soft in touch.
4. Comparable in strength with metal.s
5. Modifiable in size and shape.
6. Thermal insulated and thermal resistant.
Space suits for space walks are made
from PBI (Polybenzimidazole) non-flammable high performance fibres. The
space walk suits have various
requirements. They are employed with air
purifying and cooling systems. Each suit is tailor made for a particular
astronaut and is very expensive, as it involves the usage of various
fabrics. Circular-woven fabrics together with layered structures of
polyester, urethane and others are used. The outer layer of the suit, which
is exposed to the radiations, is made of ortho-fabrics that consist of a
blend of Gore-tex, Kevlar and Nomex materials.
As discussed earlier in the properties,
the suit should be thermal insulated as well as thermal resistant, since the
temperature range found in the space is a major hindrance. Hence the suit
should be capable of maintaining the comfortable temperature.
UV radiations, radiations of
electrically charged particles from sun and meteoroids are the other
environmental factors encountered by the astronaut in the outer space.
Meteoroids though are very small bits of rocks and metals, travel at very
high velocities and can easily penetrate into the bodies of astronauts.
Hence, the space suit of the astronaut should be capable
of having high
impact resistance and stability to withstand the major stresses caused by
these particles, pressures and others.
An Extra Vehicular Mobility Unit (EMU)
was designed by the NASA Engineers. It consists of 14 layers of structures
to perform random functions such as thermal resistant, vapour absorbing and
impact resistant layers. The inner layers of the suit do activities like
cooling and ventilation. An EMU consists of wide operations in it like;
Drink bag, communication systems, TV camera and lights, etc.
Beginning from the inner layers, first a
layer made up of knitted form of Nylon tricot is lined, over which second
layer of Spandex material fabric (a poly-urethane elastic thread) with
plastic tubing is laced. The third layer is a Urethane-coated nylon fabric
layer called the pressure bladder layer, over which a pressure-restraining
layer made of Dacron, is laced. These two layers are employed to protect the
astronauts from pressures balancing both internal and external pressures.
Above these two layers, a thin liner of nylon coated with Neoprene is
placed, followed by a series of 7 layers, thermal micrometeoroid garment of
aluminised Mylar laminated with Dacron. These 7 layers are thermal
insulated, protecting the astronaut from heat phenomenon and impact
resistant protecting from meteoroids. The final or the outer layer of space
suit, which is exposed to various radiations, is made of a blend of Gore-tex,
Kevlar and Nomex materials.
The astronauts travel to the space with
the help of spacecraft, which is designed using high performance metals and
textile composites. Based on
3D reinforcement, a narrow range of materials
is used as textile composites.
Today almost all commercial jets,
military aircrafts and space crafts encompass a wide range of textile
composites in them. The aerospacing uses the broad range of polymer
composite materials with textile reinforcements from woven, non-crimp
fabrics to 3D textiles.
The most required properties of textile
composites in aerospace structural applications are:
1. High specific modulus.
2. High specific strength.
3. Resistant to chemicals and organic solvents.
4. Good fatigue.
5. Thermal insulated and thermal resistant.
6. Impact and stress resistant.
7. Better dimensional stability and conformability.
8. Low flammability.
9. Non-sensitive to harmful radiations.
Both uni-directional as well as
multi-directional composites exhibit good properties in in-plane and
out-plane directions. Weaves, knits, braids, and stitched are the variety of
fabric structures included. It is well-known that most of the structural
failures are caused due to fatigue. Hence a low cost moulding process called
VARTM (Vacuum Assisted Resin Transfer Molding) is employed with ability to
produce complex parts, which have good impact resistance.
As per the investigations, the bi-axial
braided Carbon/Epoxy composites with different braid angles (25º, 30º and
45º) were employed for the structures of small business jet applications
whereas carbon/epoxy, unstitched, stitched and Z-pinned plain woven
composites are employed for aerospace structural applications under various
tension compression fatigue loadings.
Textile composites in aerospace
Various researchers, designers, and
manufactures are involved in the development of new products with textile
composites. Some of the textile materials are used for reinforcement of
pents and manufacture of aerospace structures are Carbon fibres, Kevlar
fibres, Alumina-boria-silica fibres and Nylon 6, 6 materials.
The following is the graph, which gives
the compressive properties of these different fibres.
It is the material consisting of
extremely thin fibres about 0.0002 - 0.0004'' in diameter and contains
mostly carbon atoms as it is produced from the pitch, which is produced as
the byproduct during the cracking process of crude oil. It is also called as
graphite fibre and its carbon percentage is almost equal to 100%. The
specific gravity of this fibre is 1.5 - 1.6. Carbon fibre is known for its
excellent tensile strength, heat resistance and chemical resistance. Keeping
in the view of these properties, these fibres are used as reinforcing
moulds, and heat insulating materials. Apart from this, these fibres are
used as raw materials for the manufacture and design of special utility
components of aviation machine, space rockets, etc.
These fibres are aligned parallel to the
fibre axis, as the carbon atoms are bonded together, when observed under
microscope. Superior to the other high performance fibres, this particular
property of crystal alignment makes the fibre strong. The raw material is
not in the fibre form, after chemical processing it is turned into the fibre
form and bundle of these fibres are twisted together to form yarn, and on
the desire of end-user it can be used by itself or can be woven into a
fabric. If this is to be used in the form of a fabric, it becomes carbonised
Kevlar narrow fabrics
Aramid fibres are a class of heat
resistant and very strong synthetic fibres, known for their good resistance
to abrasion, organic solvents and good fabric integrity even at elevated
temperatures. These fibres are better known under the trade names such as
Kevlar. Kevlar fibres are known for the ability to provide quality and
consistency, which are critical for aerospace applications.
These fibres have a very high molecular
orientation, which implies the high strength and modulus of them. Kevlar
fabrics are used in containment wraps, which perform the important role in
preventing the broken engine blades from damaging the aircraft or entering
the compartment of the passengers. These wraps, may be up to 1 kilometre in
length. These fibres are known for excellent endurance, corrosion resistance
and malleability. Alumina-boria-silica fibres The fabrics in the aerospace
structures are woven from strong
These fibres are continuous and are
specially designed to pass FAA's 2000°F (1093°C) 15-minute flame
penetration test. Nextel is a woven ceramic fabric and one of the most
widely used shielding materials. It is a commercial name for
alumina-boria-silica fibres, which shock the incoming projectiles and turn
them into small, less threatening, debris fragments. It comes in many
different styles and weights.
These fabrics are known to retain
strength and flexibility with little shrinkage even at continuous
temperatures up to 2012°F (1100°C). General aviation aircraft, large
commercial jets are vulnerable to lightning strike. FAA-certified aircraft,
for example, are typically struck once or twice a year. Unlike their metal
counterparts, composite structures in these applications do not readily
conduct away the extreme electrical currents and electromagnetic forces
generated by lightning strikes. Composite materials are either not
conductive at all (eg, fibreglass) or are significantly less conductive than
metals (eg, carbon fibre), so current from a lightning strike seeks the
metal paths available. For that reason, lightning strike protection (LSP)
has been a significant concern since the first composites were used on
aircraft more than 30 years ago.
Silicon carbide fibre
These fibres are similar to carbon
fibres, as the principal constituent repeating unit is carbon in both of
them. The tensile strength of the fibre is about 400 kg/mm². It is known
for its outstanding heat resistance, as it withstands even at temperature as
high as 1500°C. It is comparatively light with specific gravity of 2.7.
It has excellent properties like
resistance against corrosive chemicals and elasticity. Hence, today its
usage is done, in the fibre reinforcing metal compounding material (FRM) in
manufacturing special pents of aviation machines.
The Figure 14 shows the composition of
various fibres such as carbon, aramid and glass on the body segments of an
Based on the properties like strength,
resistance to heat, imparts and chemicals, these textile materials have a
wide range of applications when
concerned with aerospace structures,
1. By taking the advantage of the
stiffness and strength of carbon fibre, which is lightweight and
non-flammable, a light weight aircraft can be constructed by using some
other high performance fibres.
2. All US commercial jets have their
brakes made from carbon composites as they are the only ones, which can
withstand the high temperatures generated, if the take off is aborted all of
3. Kevlar nonwoven felt liners are being
used as fire barriers to cover the urethane foam seats on all the aircrafts
so as to prevent the production of highly toxic cyanide gases, when such
foams burn during the accidents.
4. Carbon and other high performance
fibres are used in the rocket exhausts and nose cone covers for space
shuttles, so as to protect them from
heat, from air friction during launch
5. Generally, during the launch, the
flame generated does not ignite the rocket body, as it is made from flame
resistant, graphite-carbon-textile fibre exhaust shields.
6. The white hot fumes of high
temperatures from the atmosphere friction do not consume or burn the shuttle
as some of high performance fibres and ceramic structures provide the
protection, to it which acts as shields.
7. Nylon 6, 6 of thickness 840D is used
in the type cords of jet aeroplanes, as they require to withstand strong
pressure and friction heat developed at the time of landing.
8. In order to meet demanding
temperature and strength properties of space exploration, NASA has used
alumina-boria-silica ceramic fibres. NASA and the Johnson Space Centre
together have used these ceramic textiles to protect the space station
"FREEDOM" from being punctured by space debris.
With the new advancements, the utility
of textile composites in various aircrafts predominantly increased. These
textile composites are reinforced in
the chassis, seats, wings, fans and
other parts of the aircraft. Though the percentage of usage may vary, they
vastly improve the strength, performance and fuel economy, which are the
basic credit Irion for the aircraft. Below are some of the models of
aircrafts, where the applications of textile composites are found.
1. The new Boeing 767 commercial jet
contains 46% textile composites in its body segments and the McDonnell
Douglas F-18 attack fighter uses 56% of textile composites in its body.
2. Grumman A-6 and F-14 military
fighters contain significant quantities of textile composites. The air
force's most advanced forward wing design X-29 airplane uses textile
composites in its wings, since no other material can withstand the stresses
and would easily twist off due to the winds. The Lear fan's body segments;
structural ribs and the drive shafts are made of 100% carbon fibre
3. Carbon Fibre Reinforced Plastic (CFRP)
seems to replace the universal use of Aluminum, as it is being used in
manufacturing the wings of A350, A380 and the structural components of
A400M, the new military lift plane. Many helicopter manufacturers use these
4. AIRBUS, in 1982, was first to use
CFRP to make spoilers, elevators and rudders on A310-200, and to use in
vertical fins of A310-300. Fibreglass consists of glass fibres embedded in a
resin material. It is most commonly used composite material and was first
used in Boeing 707 passenger jet in 1950s, though it comprised only about 2%
of the structure.
5.The upper fuselage of A380 is designed
from GLARE (GLAss Reinforced), which is the fibre metal laminate made from
the alternating layers of glass fibres and aluminium.
About 6.70% of the outer skin areas of
Euro fighter Typhoon are made from carbon fibre composites and the fuselage
in Boeing 787 was made from the carbon fibre composites. The fuselage is 76
feet long with 30 feet diameter.
The development of space and aerospace
textiles is a great boon to the present-day textile industry. The
manufacturers of the polymer composite component, end-users, designers,
structural material researchers and textile manufacturers are involving in
the development of new products with the usage of these textile composites.
Each new step forward is paving the way to further advancements. At the
present time, these kinds of textiles are making a significant contribution
to the increasing market for textiles. Hence, with the progressing steps and
emerging trends in the textile industry, greater attention will be drawn
from every nook and corner of the world, which ultimately improves the
economic strategy of the world to a larger extent, proving that textiles are
not only linked to the regular use of protection and safety but also to
technological advances satisfying the needs of mankind globally.
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Mr M V Ragavendra Pavan,
University College of Technology, Osmania University,
Hyderabad, Andhra Pradesh.
Mr Karthik Macharla,
University College of Technology, Osmania University,
Hyderabad, Andhra Pradesh.
Dr J Hayavadana,
University College of Technology, Osmania University,
Hyderabad, Andhra Pradesh.