Download - Air Bags Used in Automobiles
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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
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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
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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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