The Development of Airbags
Over the last few decades, airbags have become an essential safety feature which is included in every new model car. The journey of the airbag has been somewhat similar to that of the safety belt. At first there was a lot of debate regarding its efficiency at protecting the occupants of a vehicle in the event of a crash. Afterwards it was almost universally regarded as a great safe auto feature and became more and more popular with drivers and automakers until it finally became mandatory.
Most modern cars feature more than just the original airbag installed in the steering wheel. Airbags mounted in the side doors and under the seats are also common and many premium vehicles are equipped with as many as eight airbags. Dual-stage airbags are also a popular feature these days as they are able to inflate to varying degrees depending on the severity of the collision.
How It Is Made
Despite improvements in the design over the years, the airbag is still made out of three key parts: the sensor, the bag and the inflation system.
The sensor is the first part of the airbag that needs to activate. Basically, its role is to detect a collision and trigger the inflation system. It uses an accelerometer in order to make this detection, but it also has a few failsafe systems to make sure that it is not triggered by accident. The collision force necessary to trigger the airbag is equivalent to running into a brick wall at 10 to 15 mph. Therefore, minor collisions or fender benders should not trigger the airbags since it would be more expensive to replace them than it would be to fix the dents or scratches caused by the accident.
Once the sensor is triggered, the inflation system uses a combination of various chemical agents in order to inflate the bag in a fraction of a second. Currently, the compounds used are sodium azide or NaN3 and potassium nitrate or KNO3, though other chemicals have been used in the past. Their reaction creates a hot and instantaneous blast of nitrogen gas.
The last component is the bag which is inflated rapidly in order to prevent the vehicle occupants from hitting anything more solid. The bag is made out of a soft and thin nylon fabric which is folded into various areas around the car depending on where the airbag is installed. Although the explosion of the gases needs to be quick in order to be effective, it also needs to create a soft cushion which can absorb and dissipate the force of the impact otherwise the airbag would not be efficient.