Textiles in Automotive Engineering | Application of Textiles in Transportation

Posted by Firoz Kabir on Thursday, June 12, 2014 1

Transportation or automobile industry is the largest user of technical textiles with about 20 kg in each of the 45 million or so cars made every year world-wide.Textiles provide a means of decoration and a warm soft touch to surfaces that are necessary features for human well being and comfort, but textiles are also essential components of the more functional parts of all road vehicles, trains, aircraft and sea vessels. Textiles in transportation are classed as technical because of the very high performance specifications and special properties required. Seat coverings, for example, are not easily removable for cleaning and indeed in automobiles they are fixed in place and must last the lifetime of the car without ever being put in a washing machine. In trains, aircraft and passenger vessels they are exposed to much more rigorous use than domestic furniture. In addition they have to withstand much higher exposure to daylight and damaging ultraviolet radiation (UV) and because they are for public use they must satisfy stringent safety requirements such as flame retardant.

Application of Textiles in a Car or Vehicle
  • Car seat fabrics
  • Tyres
  • Seat belts
  • Door panel
  • Headliner
  • Sunvisor
  • Parecel Self
  • ABC Pillars
  • Bootliners
  • Air filter
  • Airbags
  • Heater hoses
  • Battery separators
  • Brake and clutch linings
  • Gaskets
  • Part of the suspension
  • Gears
  • Dash board
  • Carpet
  • Head board lining
  • Part of the car body
  • Crash Helmets

The most familiar technical textile in transportation is car seat fabric which is amongst the largest in volume and is growing annually in the developing world of the Pacific rim, Eastern Europe and South America Car seat fabric requires considerable technical input to produce both the aesthetic and also the very demanding durability requirements.The processes developed for car seat fabric and the technical specifications provide some indication of the requirements for seat materials in other transport applications.

Tyre:

Prime Fibers Used in Tire Making
Nylon 6,6
Nylon 6
Polyester
Rayon

 


Airbag
An airbag is a vehicle safety device. It is an occupant restraint system consisting of a flexible fabric envelope or cushion designed to inflate rapidly during an automobile collision. Its purpose is to cushion occupants during a crash and provide protection to their bodies when they strike interior objects such as the steering wheel or a window.

Air bags have been used in automobiles since the 1980s.The trend gathered momentum in the early and mid 1990s, during which major car manufacturers repeatedly boasted putting airbags in their new models for the driver. Beginning in 1998, driver-and passenger-side air bags have been required by law for all new cars in the United States.

When a car comes to a sudden stop, such as crash, the momentum of passengers depends on the speed of the car and the mass of the passenger. Because of the short time involved, the force required to stop the passengers can be very large. The goal of any supplemental restraint system is to help stop the passenger while doing as little damage to him or her as possible.

Typical Collision Force
Example:
A car travelling at 30 mph (48.6 km/h=13.5m/s) collided with another car travelling at the same speed from the opposite direction. Both cars stopped in 0.25 sec. Suppose the car weighs 2000kg.

Then the deceleration of the car is
(0-27.0)/0.25 = -108 m/s2
 
and the colliding force is
2000x108 = 216,000 N
 
If the passenger weighs 75kg, the inertia force on him/her is
75x108/2 =4,050 N

What happens to the air bag at a collision
The air bag system ignitesa solid propellant, which burns extremely rapidly to create a large volume of gas to inflate the bag. The bag then literally burstsfrom its storage site at up to 200 mph (322 kph).The gas quickly dissipates through tiny holes in the bag a second later, thus deflatingthe airbag.

The Airbag Mechanism
The bag itself is made of a thin, nylon fabric, which is folded into the steering wheel or dashboard or, more recently, the seat or door. The sensor is the device that tells the bag to inflate. Inflation happens when there is a collision force equal to running into a brick wall at 10 to 15 miles per hour (16 to 24 km per hour). A mechanical switch is flipped when there is a mass shift that closes an electrical contact, telling the sensors that a crash has occurred. The sensors receive information from an accelerometerbuilt into a microchip. The air bag's inflation systemreacts sodium azide (NaN3) with potassium nitrate (KNO3) to produce nitrogen gas. Hot blasts of the nitrogeninflate the airbag.

Generation of Nitrogen Gas
The main chemical component in the airbag is sodium azide (NaN3) together with KNO3and SiO2. In the gas generator a mixture of NaN3, KNO3, and SiO2is ignited through an electrical impulse and causes a relatively slow kind of detonation, called a "deflagration", that liberates a pre-calculated volume of nitrogen gas, which fills the air bag.

2 NaN3---> 2Na + 3N2
 
The sodium by-product of reaction 1, and the potassium nitrate generate additional nitrogen for the airbag in a second reaction
10 Na + 2 KNO3---> K20 + 5 Na2O + N2
 
These two reactions leave potassium oxide and sodium oxide to react with the third compound of the mixture, silicon dioxide, forming alkaline silicate ("glass"), which is a safe and stable, non-ignitable compound.
K2O + Na2O + SiO2---> alkaline silicate (glass)

Seat Belt 
Seat belts are multiple layer woven narrow fabrics in twill or satin construction from high tenacity polyester yarns, typically 320 ends of 1100dtex or 260 ends of 1670 dtex yarn. These constructions allow maximum yarn packing within a given area for maximum strength and the trend is to use coarser yarns for better abrasion resistance. For comfort they need to be softer and more flexible along the length, but rigidity is required across the width to enable them to slide easily between
buckles and to retract smoothly into housings. Edges need to be scuff resistant but not unpleasantly hard and the fabric must be resistant to microorganisms. Nylon was used in some early seat belts but because of its better UV degradation resistance, polyester is now used almost exclusively worldwide.


The use of seat belts is to prevent the forward movement of the wearer in a controlled manner during sudden deceleration of the vehicle.
Cars:lap and chest
Planes:lap
Racing cars:lap and shoulders


Seat fabrics 
Textile fabrics and leather are the main materials used for seat covering in the automotive industry. Fabrics have the advantage of being inexpensive and diversity for patterning. Car seat fabric design has been one of the main influences on new car buyers

The two most important technical factors governing the selection of fibres for car seat cover are the resistance to light (UV radiation) and abrasion. 
 
Fibres used include:
Nylon 6 and nylon 6,6 –rapid sunlight degradation Acrylic –low abrasion resistanceWool –expensivePolyester–good on both accounts, and occupying 90% of the market

Fabric types
Flat woven (200-400 g/m2)
Flat woven velvet (360-450 g/m2)
Warp knit tricot (piled surface, 160-340 g/m2)
Raschel double needle bar knitted (pile surface, 280-370 g/m2)
Circular knits (piled surface, 160-230 g/m2)

Manufacturing Processes
Manufacturing processesProcessing routes for the production of woven and knitted fabrics can be summarised as follows:
  • Yarn, texturise, package dye, warp/beam, weave, scour, stenter/finish, laminate, cut/sew, fit to seat;
  • Yarn, texturise, warp/beam, warp knit, brush/crop, stenter preset, scour/dye, stenter, brush, stenter finish, laminate, cut/sew, fit to seat;
  • Yarn, texturise, package dye, cone, weft knit, shear, scour, stenter/finish, laminate, cut/sew, fit to seat;
  • Yarn, texturise, package dye, cone, 3D knit, heat stabilise, fit to seat.

Composition of Car Seat Fabric
A typical car seat cover is composed of three laminated layers. The face layer is either woven or knitted

The middle layer, made from polyurethane, provides the softness of the seat cover and makes the seat cover crease free

 The backing layer, a warp knitted fabric from nylon or polyester, acts as a “slide aid” between the seat cover and the seat structure

New seat technology
The traditional way of seat making, involving cutting and sewing panels into a cover that is then pulled over the squab (seat back) and cushion (seat bottom), is time consuming and cumbersome in the modern age. Efforts have been made to develop alternative quicker and more efficient methods. Three-dimensional knitting is an option but this has had only limited usage so far.

Future development in automotive textiles

Car production was expected to remain generally static up to 2005 in the developed world, but is likely to expand considerably in the developing nations. Globally there are excellent opportunities for the multinational OEMs and their suppliers, especially those with the imagination and will to innovate new products and design features that will make car journeys more comfortable, safe and pleasant. The following paragraphs discuss the possibilities that are believed to exist. The largest growth area in automotive textiles will be in air bags as they become standard equipment in more cars. Development is needed to improve their safe functioning, however, legislation may spur on such developments in a similar way to the USA. The latest system is an air bag that deploys outwards from the occupant’s seat belt. Possible new applications for textiles within the car include the dashboard, sunvisor and seat pockets and circular knitted fabrics may be especially suited to these outlets.


Reference:
Handbook of Technical textiles (A R Horrocks and S C Anand)
Textiles in Automotive Engineering (Fung and Hardcastle)
Class Lecture Technical Textiles

About the Author

Md. Firoz Kabir(M.Sc in Textile Engineering)

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1 comment:

  1. Thanks for sharing!

    High tenacity yarns have been used in the manufacture of textiles, carpets & tarpaulin. The most important consideration in the manufacture of fabrics is the use of yarns with filaments having high tenacity and guaranteeing good foldability. Car belts that are made up of this High Tenacity Yarn polyester can give you better protect and comfortability. Buy High Tenacity Yarn from leading producers and dealers Fiberpartner. Here polyester high tenacity yarn is used for high performance applications where tenacity is the key factor. Get an perfect solution for your protection.

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