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Air Bags Used In AutomobilesSUBMITTED BY : SAHIL DEV

2CONTENT

Introduction Purpose Physics of airbag during collision Need of the airbag in connection with the safety benefits Design and construction of airbag system Types of airbag Functional characteristics required for airbags fabric Raw material and manufacturing method Finishing process Comparison of nylon and polyester airbag fabric Types of airbag fabric Development in airbag system Conclusion References

3INTRODUCTION

An airbag is an automotive safety restrain system for an occupant as well as passengers. The system consists of a flexible fabric envelope or cushion, designed to inflate rapidly during an automobile collision.

► A safety device used in the four wheelers to avoid the Head and Chest injuries from collision by providing the cushion between the occupants.

4PURPOSE

To protect occupants during a crash and provide protection to their bodies when they strike interior objects such as the steering wheel or a window

Protect the head and upper body from hitting to steering wheel compared to seat belt alone. Airbag have reduced death by 28%, serious injury by 29% and hospitalization by 24%

5PHYSICS OF THE AIRBAG DURING COLLISION

The Inertia Theory : If an object moving at a constant velocity continue at the same velocity unless an external force acts upon them. This law, known as the law of inertia, is demonstrated in the car collision.

Based on Newton’s law:F = m ( -V/∆t )Where,F = Force on the bodym = Mass of the object (Body)Vi = Velocity of the moving object (After collision it will decrease)a = (V/∆t) = Acceleration (After collision it will decrease)

6CONTINUE…

The injury can be avoided by reducing the force on the body. This can be done by two ways as :

By increasing the time interval (∆t) over the force being applied

7CONTINUE…

By spreading the force over large area of the body

Distribution of force over body

8NEED OF AIRBAGS IN CONNECTION WITH THE SAFETY BENEFITS Reduction by 26% in moderate to serious injuries by airbags and

seatbelts together than only by seat belt.

Airbad and belt Belt alone0

20

40

60

80

100

Percent reduction in moderate to serious head injuries (Compared to drivers using no restraining safety equipment)

9DESIGN AND CONSTRUCTION OF AIRBAG SYSTEM

There are three parts to an airbag that accomplish this action Airbag itself Crash sensor Inflating system

10AIRBAG INFLATION SYSTEM

The sensor sends the electric signal to burn the propellant kept here to generate the gas

Monitors the readiness of the airbag system A device that stores enough electrical energy to deploy the

airbag if the vehicle’s battery destroyed in it

11CHEMISTRY BEHIND AIRBAG

Mainly two types of gas are used : Nitrogen gas based airbags

NaN3 (S) ======> 2Na (S) + 3 N2 (G)

10 Na (S) + 2 KNO3 (S) ======> K2O (S) + 5Na2O (S) + N2 (G) ↑

SiO2 (S) + K2O (S) + Na2O (S) ======> K2SiO3 (S) + Na2SiO3 (S)

Carbon dioxide gas based airbags

NaHCO3 (S) + CH3COOH (Aq) ======> CO2 (G) + CH3COONa (Aq) + H2O(L)

12OPERATION SEQUENCE OF AIRBAG

Collision Sensing and inflation Fully deployed Deflation

13TYPES OF AIRBAG

Driver side airbag Passenger airbag Knee airbag

14TYPES OF AIRBAG

Curtain airbag Side thorax airbag Door mounted side airbag

15THE FUNDAMENTAL CHARACTERISTICS REQUIRED BY THE AIRBAGS FABRIC

High bursting strength Good fire retardancy Light weight Compact folding ability Low cost Reduced skin abrasion (Softness) High tear propagation resistance Resistance against ageing Defined dimension stability Air seal ability i.e. low air permeability Good coating adhesion Good fog resistance

16RAW MATERIAL AND MANUFACTURING METHOD

Following multi-filament are used Nylon 6 Nylon 6,6 Polyester PA 46PA 46 has higher melting point (285ºC) than Nylon 66 (260ºC) but cost of PA 46 is higher

Fiber YarnFabric

Silicone others

17FINISHING PROCESS

Cutting the fabric in required shape by laser Sewing by nylon-66, polyester and Kevlar aramid yarns

Desizing Calendaring

Heat set

Inspection Cutting

18NYLON V/S POLYESTER

Properties Nylon 6,6 Polyester

Specific heat capacity (kJ/kg/K) 1.67 1.3

Melting Point (ºC) 260 258

Softening Point (ºC) 220 220

Energy to melt (kJ/kg) 589 427

Density (kg/m3) 1140 1390

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Fabric coverage is reduced for the polyester fabric that gives less thermal protection to the passenger.

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Low heat capacity of polyester at 400ºC temp for 2 second Poor ageing performance of polyester in hydraulic degradation

behavior

21CONSTRUCTION DETAILS FOR AIR BAG FABRICS

Driver side Passenger Side25 x 25 plain weave840 D nylon 6,6Scoured, heat set, coated

25 x 25 rip stop840 D nylon 6,6Scoured, heat set

46 x 46 plain weave420 D nylon 6,6scoured, heat set, coated

41 x 41 plain weave630 D nylon 6,6Scoured, heat set49 x 49 plain weave420 D nylon 6,6Scoured, heat set

Typical characteristics of driver and passenger side fabrics used in airbags (Courtesy of AlliedSignal)

22CONSTRUCTION DETAILS FOR AIR BAG FABRICS

Parameters Uncoated Coated(Epi x Epi) 25 x 25 25 x 25Thickness 0.013 0.107Weight (oz/ sq. yd) 5.69 8.30Tensile strengthWarpFilling

533549

450478

ElongationWarpFilling

33.635.3

2838

Tongue tearWarpFilling

199.4192.5

8583

Typical properties of 840 Denier, nylon 6,6 Airbag Fabric (Courtesy of AlliedSignal)

23TYPES OF AIRBAG FABRICS

Coated airbag fabrics Uncoated airbag fabric Needle punched airbag fabrics Woven and nonwoven combined airbag fabric One sided laminated woven and nonwoven combined airbag

24COATED AIRBAG FABRIC

Coating substances elastomeric material as Neoprene Silicone

25ADVANTAGE OF SILICON OVER NEOPRENE

Needed in half amount so lighter, pliable, less thicker fabric More chemically competitive and cheap with nylon Better heat resistance and stability Prevents burn through (Pinholes) so maintains air permeability of

the fabric

26THE PROBLEMS WITH COATED WOVEN FABRIC AIRBAG

Formation of bubbles during coating Breakup of film due to non integration of film and fabric Injury to face skin Irregularities during coating Recyclability of the airbag becomes difficult Fabric becomes stiffer

27UNCOATED AIRBAG FABRIC

Woven in a manner that creates a product possessing low permeability

Provide calendaring treatment to reduce permeability Extrusion coated with a thermoplastic material to make them air

impermeable

28ONE SIDED LAMINATED WOVEN AND NONWOVEN COMBINED AIRBAG

Offer air seal ability and fire retardancy while being lightweight Heavy weight per unit area Reliability of the air bag is poor, are not solved

29NEW DEVELOPMENT IN AIRBAG SYSTEM

Lower Leg Airbag : Autoliv’s Inflatable Carpet protects the car occupant’s feet, ankles and lower legs in frontal crashes by removing the feet from the intruding foot well of the vehicle

30CONTINUE…

Radial Deployment System (RDS) : Airbag (Umbrella RDS) coves the steering wheel-saves the short person

31CONCLUSION

Airbags is one of the inevitable components in car and vehicles to safeguard drivers and passengers as per present applications. SO selection of material is key feature for airbag manufacturing

Airbags made from nylon 6,6 are more popular due to their inherent properties of strength, energy absorption, thermal resistance and environmental stability

Textile and automobile industry may provide effective safety to the drives and passengers during driving time

32REFERENCES

1. Aravin P. Periyasamy & Moin Khan, "Theory Behind In Air Bags Application in Automobiles”.2. Khan. M. S, project done by DKTE students, online launched on Textile review, “Air bags for automobiles . 3. Kunal Singha, “Strategies for in Automobile: Strategies for Using Automotive Textiles-Manufacturing

Techniques and Applications”, Journal of Safety Engineering 2012, 1(1): 7-16 9. Indian textile research journal, “Airbags & airbag textiles”.

4. Dupont , Sun. J, Barnes J. A, Airbag End-Use Technology, “Material selection for Air-bags” , pp 1-8.5. Tasnim N. Shaikh, Satyajeet Chaudhari and Hiren Rasania ,“Air Bag: A Safety Restraint System of an

Automobile”, Department of Textile Engineering, Faculty of Technology & Engineering, The Maharaja Sayajirao University of Baroda, Vadodara, Gujarat, Indi

6. S.Adanur, “Wellington Sears Handbook of Industrial Textiles”, Technomic, Switzerland, Ed. 1st edition, 1995, 500-5 Aravin P. Periyasamy & Moin Khan , “Theory Behind In Air Bags Application in Automobiles”.

7. Walter Fung And Mike Hardcastle , ‟Textiles in automotive engineering Woodhead” Publishing Limited.8. Mukopadayay, S.K., and Partridge, J.F., “Automotive Textiles”, 1997, Textile progress, 29(12), 29-34.9. Prof. P.A. Khatwani, Mr. S.S. Yardi NCUTE- programme on “Technical textile”. 10. http://textilepapers.tripod.com/airbags.htm11. http://www.autoevolution.com/news/how-airbags-work-6362.html

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