textile structures in technical applications

8/12/2019 Textile Structures in Technical Applications

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Textile structures in technical applications.

Sanjiv Kasar*, Vijay Goud ,

Department of Textiles

D.K.T.E.S.Textile&Eng. Institute, Ichalkaranji-416115(M.S), India.

and

Balgonda Patil

Asst.Manager ,Capitol Nonwovens, Nasik

*Corresponding author Email: [email protected]

Abstract

Technical Textiles today are increasingly becoming the foundation of the world

around us. Principles of textile science and technology are merged today with other

specialties such as engineering, chemistry, geotechnology, material/polymer science

to develop solutions unimaginable a century ago. This has enabled us to revolutionize

the textiles produced from the same conventional techniques of weaving, knitting,

braiding, embroidery, rope making and nonwovens. Industrial fabrics share the

precision, delicacy and exact repetition of detail characteristic of twenty first century

machine art. The aim of this review is to discuss use of textile structures in technical

applications enabling to achieve lighter, flexible, smarter, durable,safer and faster end

products.

Introduction

Textiles are known to mankind since or earlier than 7000 BC. The knowhow of

textiles is older than metal working or pottery making, perhaps even older than

agriculture. The conversion of fibre to yarn and yarn to fabric for apparel, household

and decorative purposes still represents majority of textile applications. Textile

structures as known are composed of fibres, yarns and fabric.

Textiles today are omnipresent. They are found in roadbeds, as reinforcement

in concrete columns or they may be implanted into humans. Technical applications


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are high performing, purely functional and precisely engineered fabrics representing a

very small volume of the enormous textile industry.

As, innovation is a road with no end; a separate branch of textiles is shifting

towards performance specific applications. Technical applications as they may becalled require textile structures to be Stronger, Faster, Lighter, Safer and Smarter.

Technical applications require textiles to be stronger than steel, faster than words,

lighter than air, safer than chain mail, and smarter than a surgeon. This ultimate textile

structure can be a woven, knitted, braided or a nonwoven structure.

Technical Applications

Technical applications are those where aesthetic and decorative qualities are not a

requirement, but a highly performance based, purely functional precisely engineered

fabric is a vital component. Technical applications involve use of high performance

fibres. High performance fibres have exceptional strength, high strength to weight

ratio, chemical or flame resistance or range of operating temperatures. High

performance fibres used in technical applications are glass, ceramic, carbon, aramids,

vectran, HMPE, PBO, PIPD, hybrids. Polyester fibre gives a 50% increase in strength

over cotton, whereas high performance fibre like Kevlar delivers 300% increase instrength and 1000% increase in stretch resistance.

The development of high performance fibres caused Engineers and Designers

to re-examine the structural capabilities of traditional manufacturing methods such as,

weaving, braiding, knitting, embroidery and nonwovens. The use of these textile

structures in technical applications are discussed in the paper.

Weaving

Plain woven fabric; the simplest of textile structures has greatest strength and stability

of traditional fabric structures. Plain woven airbag was used to protect MER(Mars

Exploration Rover ) on their descent and landing on surface of Mars. The first

impression made by man on the soil of Mars was that of a plain woven fabric; an

impression made by impact of airbags on the surface of Mars (fig.1).This airbag fabric

had a double bladder and several abrasion resistant layers made of tightly woven


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vectran. Vectran, the liquid crystal polymer is a high performance fibre having high

specific strength and high specific modulus. Weight is of premium importance for all

the materials used for space travel and vectran provides an equal strength at one -fifth

of weight of steel. The material used for protection of MER, had to perform at severe

temperature fluctuation which occurs in a very short period of time. Prior, to impact

of airbags on the mars surface, gas has to be inflated in the airbags(fig.2). This

inflation of airbags raises the temperature inside the airbags to 2120F.

Figure 2 :Mars Pathfinder lander airbag prototype.

In the immediate vicinity of two to three seconds of inflation of airbags it strikes the

surface of the mars whose temperature is minus (-)1170F. Vectran provides optimum

performance at these low temperatures too. Along with vectran; Kevlar 129 was used

which provides for the tethers inside the airbags because of its superior performance

Figure 1: MER lander airbag system& its impression left on Mars surface.


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at high temperatures. Rover used on this mission was also textile based; it was made

from super strong, ultra-light weight carbon fibre composites which are used for

airspace applications as well as high performance sports equipment.

As composite reinforcements, textiles offer a high level of customization withregard to type and weight of fibres.It is well known fact that fibre strength is greatest

along the length. Thus use of combination of fibres and use of different weaves to

maximize density of fibres in a given direction will result in more strength.The

strength of a composite material is derived from the intentional use of this directional

nature. Glass fibres are mostly used for high performance products but carbon or

aramid or combination of these two give superior strength and lighter weight. The

advantage of a composite construction is the ability to make a complex form in one

piece, called as monocoque construction. A woven textile is hand laid in the mould;

the piece is wetted out with resin and cured in auto clave. The same drape and hand

that makes twill the preferred weave for most apparel is also desirable for creating

complex form of boats, paddles, bicycle frames and other sports equipment. Boat

builders prefer carbon fibre composites for making racing shells (fig.3).

The critical factor in shell design is stiffness to weight ratio, with greater stiffnessmeaning that more of the rowers power is translated into forward motion. Glass,

carbon, boron provides higher stiffness to weight ratio. Twill and satin woven fabrics

Figure 3:Light weight carbon composite single shell


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made of high performance fibres (glass, carbon, and boron) are used for construction

of shells. The satin weave is very dense, with nearly five times as many yarns per inch

as plain weave. This density minimizes risk of pin holes forming in composites,

keeping boat watertight. Glass material is exceptionally fine and light which allowstextile to be wetted out with a smaller amount of resin, giving a lighter finished

product. An aramid honeycomb is sandwiched between two layers of this fabric and

then reinforced with unidirectional carbon fibre tape. The boats from these materials

are as light as 26 lbs. compared to 32-40 lbs. for wooden shells.

In case of cycling competition, Total Eclipse Bicycle frames (fig.4) are gaining

impetus which is a monocoque frame, made from resin impregnated carbon fibre twill

woven fabric. This frame not only provides suspension to the rider seat helping to

reduce the rider fatigue, but also gives excellent stiffness to convert pedalling energy

into speed.

Figure 4:Total Eclipse Bicycle frame

The process of handling a woven fabric in a mould is extremely time consuming

and efforts are being made throughout composite industry to create pre forms

meaning, textiles that can be manufactured in a shape required for finished product.

Braiding and knitting technology is useful in this regards and special techniques are

developed to design 3 D tube which will act as a pre form.


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Braiding:

Braiding is an at least 1000 years old technique for plaiting of hair, the making of

buckets and creation of sturdy straps and cloths. Unlike weaving, in which the fibres

cross at right angles, the elements of a braid meet at oblique angles. They take threedimensional forms easily and distribute the loads and stresses efficiently throughout

the structure due to continuation of braiding filaments; end to end.

Conventionally braiding technique is used for laces, ropes, hose making. When

adopted for the advance purposes the seamlessness of braided form is critical and also

creation of strong, leak proof inflatable structure becomes necessity.

One of the new uses of braided structure is Festos Fluidic Muscle, which behaves

like industrial- strength human muscle (fig.5).A braided hose, with Aramid fibres laid

at oblique angles to one another and encased in a rubbery sheath is used in making of

a shaft. This shaft acts as a muscle which is a hydraulic or pneumatic actuator which

itself operates on a membrane contraction system.

Figure 5: Walking machine with Festo Fluidic Muscles


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The hose shaft contracts when internal pressure of air or fluid results in alteration

of the interlacing fibres angle. As there are no moving parts as in conventional piston

type actuators, the movement is free from associated jerking. The muscle can exert ten

times more force and its weight is about one eighths of a metallic cylinder of the sameinner diameter. The smooth operation makes it ideal for precision robotics; combined

with its light weight.

In another application an air beam is designed by Vertigo Inc. which is an

inflatable support beam developed for U.S. Army (Fig.6).

Figure 6: Seamlessly braided Vertigo's Air Beam

Vectran fibre is used to give high strength with good flex-fatigue resistance. The

flexibility of the fibre is very useful in repeated inflation and deflation as well as

packing and shipping.

A mast for racing yacht has a complex shape. It is a columnar but narrower at the

top and a larger softly triangular shape at the base. Carbon fibres are laid at vertical or

zero degree position, glass fibres are added at 45 degree and finally carbon fibres are

wrapped at 90 degrees. The carbon fibre gives strength while glass minimizes the

deflection or crimping of vertical carbon elements. The 90 degree wrapping gives

strength against bending stresses which could cause the tube to deform or collapse.


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Thus over braiding technique also allows variation in the number of layers or wall

thickness (fig.7).

Figure 7 : Braided Mast construction made out of carbon and glass high performance fibres

A considerably more complex structure is a composite rotor blisk for rocket engine

turbo pump made by braiding technique. It works as a replacement for a metal part

due for reduced machining and continuity of structure (fig.8).

Figure 8: Rotor Blisk

Knitting:

Knitting is also an old technique where in the knit stitches are used to make a

fabric or pattern with looping technique. Because of this looped structure these fabrics

are easily stretched (distended) in either direction. This bidirectional distortion gives


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comfort while bending and flexing of body parts; even if they are not dimensionally

stable as plain woven fabrics.

This property of knit garments is used to engineer a warp knit mesh bag which can

be used as support to treat enlargement of heart (fig.9).

Figure 9:Cardiac Support Device

In case of coronary diseases, the heart has to work harder to pump the blood.

During this process the heart muscles get damaged causing the enlargement. A knitted

bag supports the heart to prevent enlargement and also allow it to beat normally.

Care is taken to use untwisted yarns which will not damage the heart flesh and also

to attach antibiotics to the knitted structure by special dyeing techniques.

Thus a knitted support bag is safe for heart and also reduces the time of surgery by

better flexibility and handling.

Embroidery

Embroidery is surface technique allowing placement of threads in any position or

direction on a base cloth enabling to make drawing like textile structures. Moreover, if

appropriate design features are incorporated into embroidery design, the base cloth

can be dissolved away, leaving an open structure. Within medical context, rapid

customization takes on new implications.


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Modern embroidery uses sophisticated software. Recently, advantages of

embroidery have been explored for creation of surgical implants.Knitted and woven

surgical devices have been successfully implanted but some needs are not fully

addressed by these techniques. New solutions focus on structurally biocompatibleimplants, combining engineering principles with those of life sciences.

Figure 40:Bioimplantable embroidered surgical devices

The oriented fibres can be used to mimic natural fibrous arrays ligaments, and to

match mechanical properties of implants to the demands of host tissue. Embroidery

also allows the primary function of such implants- the transference of loads to be

achieved by a thread or group of threads, which can be structurally integrated with

other features such as eyelets for the insertion of screws or open mesh areas to

promote tissue in-growth. Integrated eyelets provide a way of effectively dispersing

the strain of the attachment point without compensating the textile (fig.10).

Bespoke fibre placement is unique to embroidery in the sphere of traditional textile

manufactured but is being executed on a much larger scale on highly unconventional

equipment with 3 DL (Trade Mark of North Sales Nevada) manufacturing process.

Laminate sails are used in racing. In this method, fibres are laid in sheet of Mylar in


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grid pattern and these laminates are cut and sewn like ordinary cloth. The grids do not

permit spatial variations in fibre density or orientation and the seams compromise the

strength of sails, negating some of advantages of high performance fibres. By

contrast, 3 DLsails are made as a single piece on an enormous adjustable mould to theprecise aerofil shape ideal for each boat. Unlike, the formal symmetrical

microstructure of woven fabrics, this process embraces asymmetry; making lightest

possible sail by putting fibre anywhere it is needed. This allows sails to carry

astronomical loads; the corner loads on many racing sails are in excess of ten

thousand pounds. The fibre laying gantries travels over surface of sail moulds laying

down carbon and aramid fibres on Mylar scrim (film) just as stitch head of an

embroidery machine (fig.11). The placement of the fibres reflects the anticipated wind

forces and variations in stress field, and optimizes local strength and stiffness.

Figure 11: Fibre laying Gantries used similar to stitch head of an embroidery machine

Ropes

Ropes made from natural fibres could not withstand heavy engineering uses. Steel

wire ropes were thus used for heavy engineering end uses. Nylon and polyester ropes

were also used as engineering ropes. For the same strength, these ropes were about

half the weight of the steel ropes but with twice the diameter. Ropes made from high


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performance fibres such as aramid, HMPE, Vectran, and polyphenylene

benzobisoxazole (PBO) with diameter similar to steel but in one-tenth of its weight.

Ropes made from natural fibres have to be highly twisted together to prevent fibres

sliding over one another, this is unnecessary with continuous filament yarns. Newlow-twist constructions, with just enough twist to give coherence to ropes have been

developed. In applications, where rope needs to stretch and absorb high-impact

energies, nylon and polyester are design choices and where resistance to extension is

needed; the newer high modulus fibres are preferred.

Figure 5 : Marlow super line polyester rope

In, the most demanding applications fibre ropes are now competing with steel. The

polyester ropes are used to moor about 20 oil rings in deep water off the coast of

Brazil. The great advantage of polyester is its low weight compared to steel. Among,textile fibres, PET has right balance of properties, rugged durability and enough

extensibility to prevent large tensions developing as rigs rise and fall. Marlow

superline polyester rope with a diameter of ten inches and breaking load of two

thousand tones is one of the strongest fibre rope made (fig12).


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Nonwovens

These are fibrous constructions similar to wool felt, and are fastest growing area in

textile industry. In nonwovens technique, precursor polymers are transformed throughfibre stage directly to textiles in a single manufacturing process.

Nanotechnology is emerging profoundly and it is manipulation of the materials at

the atomic level. Textiles made from nanofibres, each of over 1/180000 of the breadth

of human hair, offer very small fibre diameter and pore size, high absorption, and a

large number of chemical functional groups along their molecular chains. This

combination of properties has far reaching implications in filtration, health care,

energy storage and bio-engineering. The very large surface area provides infinite

attachment points for molecules. These advantages can be utilized in drugs for a

bandage; clothing based drug delivery system, reactive molecules capable of sensing

chemical hazards in the environment. The large surface area could also allow for

entrapment of molecules in all varieties of filtration applications such as air, chemical

and blood. Nanoscale fibres made from carbon called carbon nanotubes, have bonds

stronger than those in diamonds. A fibre that is 60% nanotubes is 20 times tougher

than steel. Since, carbon tubes have electrical properties, they could be pivotal in

creation of responsive materials and molecular scale electronic device.

Nanofibre membranes are generally produced by electrospinning, in which a

liquid polymer solution is drawn towards a highly charged metal plate, pulling it into

nanoscale fibres. Research is also being carried out with bio-polymers such as

collagen and elastin, both of which occur naturally in human body. The superfine

network of fibres provides an ideal scaffold for tissue engineering, for replacement of

damaged organs or tissues. A collagen tube made by electro spinning technology

could be six times smaller than smallest available graft and could grow with patient

(fig.13).


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Figure 6:Electrospun fibre mat spun on a mask

The idea of manipulating materials at the nanoscale, of integrating functionality at

atomic levels, blurs line between what materials are and what they do.

Conclusion

Textile technologies are undergoing a profound change. Textile structures in technical

applications are creating a new market potential. Textile structures to be used in

technical applications are precisely engineered products, designed with specific end

use fibres ; thus giving high performance and leaving very less or no room for defectsin these products. Unexpected, creative and successful consideration of textiles by

engineers and designers in widely diverse fields assures that these extreme textiles

will remain the materials that shape our future world.

References :

1. Matilda McQuaid, Extreme Textiles: Designing for High Performance,Published by Princeton Architectural Press 2005.

2. http://morocz.com/BoatBuilding/mast02.htm Krakenbaitgets a carbonfiber mast - part 2.

3. http://os.typepad.com/my_weblog/2006/08/nanofabric.html

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