Seminar on Airbag Systems Report Pdf Free Download
The present paper represents a brief review of life saving system in roll- over accidents, while driving on the road by a four wheeler. An Airbag is an automotive safety restraint 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. 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 etc. Thus it lowers the number of injuries by reducing the force exerted by steering wheel, windows and the dashboard at any point on the body. Continuing research and developments are going on in its module design, combustible material, air bag fabric design and material, coating etc. in making this life saving safety device further efficient. However, success of any safety restraint device depends on its correct implementation and certain safety rules to be followed.
For many years, the trusty seat belt provided the sole form of passive restraint in our cars. Seat belts have been proven to be effective in saving lives and preventing or lessening injuries in automobile accidents.. The first passive restraints were modifications of seat belts themselves; the belts were coordinated with operations of opening the car doors and starting the automobile, which caused belts built into tracks in the doors to wrap around the driver or passenger when the seat was occupied. Concurrently, the airbag was devised as a secondary form of passive restraint during impact.
Air Bags have been under development for many years. They were initially used and designed to be used in fighter planes during world war second. In the 1980’s the first commercial air bags appeared in automobiles. Since 1988, all new cars have been required to have air bags on both driver and passenger sides. To date, Statistics show that air bags reduce the risk of dying in a direct frontal crash by 30 percent. Other than steering Wheel mounted or Dash board mounted bags, there are seat-mounted and door mounted side air-bags. Air bags were invented as the result of serious government discussions and industry research and tests.
The air bag system consists of three basic parts- an air bag module, crash sensor and a diagnosis unit. Some systems have ON/OFF switch to deactivate air bag system.
The air bag module fig no:3.1 contains both an inflator unit and the lightweight fabric air bag. The driver air bag module is located in the steering wheel hub, and the passenger air bag module is located in the instrument panel. When fully inflated, the driver air bag is approximately the diameter of a large beach ball. The passenger air bag can be two or three times larger since the distance between the right-front passenger and the instrumental panel is much larger than the distance between the driver and steering wheel.
Air bag production process
Typical manufacturing line for air bag has been shown fig no: Airbags can be manufactured by either of the mechanisms of fabric manufacturing, weaving and non- woven fabric manufacturing process
airbag fabric should possess following quality parameters:
- Small fabric thickness.
- Low specific fabric weight.
- High tenacity in warp and weft direction as well as toughness.
- High tenacity for furthers tearing
- High elongation.
- Good resistance to aging.
- Heat resistance up to 190 0C.
- Good resistance to UV light.
- Low and very even air permeability.
- Reduced cost.
- Precisely controlled gas permeability.
- Excellent seam integrity.
- Improved pliability and pack height
- Reduced value or burn through resistance.
The first stage of the airbag deployment is the accident itself. The collision, be it frontal or lateral, activates an array of sensors in the vehicle, including accelerometers, impact sensors, side pressure sensors, brake pressure sensors, and seat occupancy sensors. All these sensors are in intimate connection with the ACU (Airbag Control Unit). The unit decides if and how to deploy the airbags. When the ACU detects that the deployment threshold has been reached, it initiates the inflation stage. As the compressed air system would have been impractical and quite inefficient, engineers came up with an idea quite similar to the working principle of the solid rocket booster.
Each airbag incorporates a pyrotechnic device, known as an initiator or electric match, consisting of an electrical conductor cocooned in combustible material. A current pulse heats up the conductor, which in turn ignites the combustible material. This igniter triggers the chemical reaction that actually fills the nylon fabric airbag with gas. The large volume of gas then forces the airbag out of the steering wheel and/or dashboard at a speed of up to 200 mph or 322 mph, the whole process taking about 0.04 seconds. Considering that the blink of an eye is approximated at 0.2 seconds, one could say it’s quite a speedy process The last stage of the airbag process is the deflation, which occurs almost immediately after the inflation is completed. The gas escapes through special vents. They also prevent the occupants from suffering major impact injuries. Another effect of the deflation is the release of dust-like particles, mostly cornstarch and talcum powder that are used to lubricate the airbag. Small amount of Sodium hydroxide may initially be present. This chemical can cause minor irritation to the eyes and/or open wounds; however, with exposure to air, it quickly turns into Sodium bicarbonate (common baking soda). Depending on the type of air bag system, potassium chloride (a table salt substitute) may also be present. Initially, the chemicals used in airbags were a major health concern, but present systems will only produce a mild irritation of the throat and eyes for most people, as an outcome of dust released. Generally, these minor irritations continue up to the time occupant remains in the vehicle with the windows closed and no ventilation. Once deployed, the air bag cannot be reused and should be replaced by an authorized service department.
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