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Side Airbags

Side-impact airbags are usually located in the backrest of the seat, and inflate between the door and the seat occupant.
​Side airbags are estimated to reduce serious chest injuries in side-impact collisions by approximately 25%. 
The protective effect is obtained by keeping the occupant away from the impact zone, and dampening the blow from the intruding side of the vehicle. Since the occupant is kept away from the intruding vehicle side, protection of the head is also improved.
For adequate head protection, however, special airbags are required. 
Side airbags are typically installed in the back rests of the front seats or behind the door trim, and inflate between the seat occupant and the door. The advantage of having the airbag module mounted in the back-rest is that it will move with the seat and therefore give optimal protection for sizes of occupants. The airbag can deploy either trough a visible cover or burst trough the stitching in the back-rest. 
There are different types of side airbags depending on the protection area and type of vehicle:

Thorax side airbags


The bag usually has a volume of only 8 to 12 liters to make it as gentle as possible but still efficient enough to provide required protection. 
The thorax bag is inflated within 12 thousands of a second; four times faster than a frontal airbag. The bag is inflated at a certain crash threshold, usually corresponding to a speed of the impacting vehicle of more than 15-20 km/h.
Head thorax side airbags​

Head Thorax Side Impact Airbag works as a Thorax module. It offers a combined head and thorax protection in side impact collisions for one occupant and is often used where the Inflatable Curtain (IC) (that also provides protection in rollovers as well as for near-seat occupants) cannot be mounted, such as in convertible cars.


These airbags are designed to reduce the risk of injury to the thorax and pelvic regions. To achieve this improved protection, the airbag coverage area is extended by adding a cell which is inflated to a higher pressure in order to distribute load over the thorax and pelvis parts of the occupant's body more efficiently.
This concept takes advantage of the pelvis' ability to take higher loads, while it limits pressure on the sensitive thorax/abdomen area.
Because the distance between the occupant and the car's stiff parts is so small, this side airbag deploys very fast (within a very few milliseconds) so that it will be in protective position very early in the crash. The Pelvis-Thorax airbag is located in the back-rest frame of the car seat.

Door Mounted Inflatable Curtain


Many convertible vehicles use head-thorax bags for side impact protection. These are thorax bags with an extension that inflates upwards to protect the head. But the extension can be wobbly since it is not attached to any roof pillars. There is also a risk that the occupant's head misses or slides off the relatively narrow head extension.
To address these drawbacks, Autoliv developed a specially designed Door-Mounted inflatable Curtain (DMIC) for convertible vehicles. This airbag is made up of a multitude of small cells in three layers (like a beehive). This ingenious structure gives it unsurpassed stability and as a result it can be used in different situations, such as rollovers, since the structure is strong enough to hold the occupants safe inside the vehicle in many severe accidents.