Air Bags Used in Automobiles

This slide include various type of airbags used in automobiles, their types, advantages and etc.

1. Air Bags Used In Automobiles Submitted by : Sahil DEV 1

2. CONTENT 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 2

3. INTRODUCTION 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. 3 A safety device used in the four wheelers to avoid the Head and Chest injuries from collision by providing the cushion between the occupants.

4. PURPOSE 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% 4

5. PHYSICS 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 body m = 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) 5

6. CONTINUE… 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 6

7. CONTINUE… By spreading the force over large area of the body 7 Distribution of force over body

8. NEED 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. 8

9. DESIGN AND CONSTRUCTION OF AIRBAG SYSTEM There are three parts to an airbag that accomplish this action Airbag itself Crash sensor Inflating system 9

10. AIRBAG 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 10

11. CHEMISTRY BEHIND AIRBAG M ainly two types of gas are used : Nitrogen gas based airbags NaN 3 (S) ======> 2Na (S) + 3 N 2 (G) 10 Na (S) + 2 KNO 3 (S ) ======> K 2 O (S) + 5Na 2 O (S) + N 2 (G) ↑ SiO 2 (S) + K 2 O (S) + Na 2 O (S ) ======> K 2 SiO 3 (S) + Na 2 SiO 3 (S ) Carbon dioxide gas based airbags NaHCO 3 (S) + CH 3 COOH (Aq ) ======> CO 2 (G) + CH 3 COONa (Aq) + H 2 O(L) 11

12. OPERATION SEQUENCE OF AIRBAG Collision Sensing and inflation Fully deployed Deflation 12

13. TYPES OF AIRBAG 13 Driver side airbag Passenger airbag Knee airbag

14. TYPES OF AIRBAG 14 Curtain airbag Side thorax airbag Door mounted side airbag

15. THE 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 15

16. RAW MATERIAL AND MANUFACTURING METHOD Following multi-filament are used Nylon 6 Nylon 6,6 Polyester PA 46 PA 46 has higher melting point (285ºC) than Nylon 66 (260ºC) but cost of PA 46 is higher 16 Silicone others

17. FINISHING PROCESS Cutting the fabric in required shape by laser Sewing by nylon-66, polyester and Kevlar aramid yarns 17

18. NYLON 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/m 3 ) 1140 1390 18

19. CONTINUE… Fabric coverage is reduced for the polyester fabric that gives less thermal protection to the passenger. 19

20. CONTINUE… Low heat capacity of polyester at 400ºC temp for 2 second Poor ageing performance of polyester in hydraulic degradation behavior 20

21. CONSTRUCTION DETAILS FOR AIR BAG FABRICS Driver side Passenger Side 25 x 25 plain weave 840 D nylon 6,6 Scoured, heat set, coated 25 x 25 rip stop 840 D nylon 6,6 Scoured, heat set 46 x 46 plain weave 420 D nylon 6,6 scoured, heat set, coated 41 x 41 plain weave 630 D nylon 6,6 Scoured, heat set 49 x 49 plain weave 420 D nylon 6,6 Scoured, heat set 21 Typical characteristics of driver and passenger side fabrics used in airbags ( Courtesy of AlliedSignal)

22. CONSTRUCTION DETAILS FOR AIR BAG FABRICS Parameters Uncoated Coated (Epi x Epi) 25 x 25 25 x 25 Thickness 0.013 0.107 Weight ( oz/ sq. yd ) 5.69 8.30 Tensile strength Warp Filling 533 549 450 478 Elongation Warp Filling 33.6 35.3 28 38 Tongue tear Warp Filling 199.4 192.5 85 83 22 Typical properties of 840 Denier, nylon 6,6 Airbag Fabric (Courtesy of AlliedSignal)

23. TYPES 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 23

24. COATED AIRBAG FABRIC Coating substances elastomeric material as Neoprene Silicone 24

25. ADVANTAGE 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 25

26. THE 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 26

27. UNCOATED 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 27

28. ONE 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 28

29. NEW 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 29

30. CONTINUE… Radial Deployment System (RDS) : Airbag (Umbrella RDS) coves the steering wheel-saves the short person 30

31. CONCLUSION 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 31

32. REFERENCES Aravin P. Periyasamy & Moin Khan, "Theory Behind In Air Bags Application in Automobiles”. Khan. M. S, project done by DKTE students, online launched on Textile review, “Air bags for automobiles . 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”. Dupont , Sun. J, Barnes J. A, Airbag End-Use Technology, “Material selection for Air-bags” , pp 1-8. 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 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”. Walter Fung And Mike Hardcastle , ‟Textiles in automotive engineering Woodhead ” Publishing Limited. Mukopadayay, S.K., and Partridge, J.F., “Automotive Textiles”, 1997, Textile progress, 29(12), 29-34. Prof. P.A. Khatwani, Mr. S.S. Yardi NCUTE- programme on “Technical textile”. http://textilepapers.tripod.com/airbags.htm http://www.autoevolution.com/news/how-airbags-work-6362.html 32

33. THANK YOU 33