Airbag Injury

(Vehicle Safety Devices – Making Them Safer)
By: Perry J Zucker – February 2, 2013
Each year there are approximate 10 – 21 million  motor vehicle accidents (1980 – 2010) that occur.  It is the engineer that has an engineering and science background along with other education, that can investigate these accidents.
Safety Devices
1) Seat Belts: Most newer vehicle has three (3) point system; shoulder / lap and pretensioner (pyrotechnics to trigger /  spring loaded).
2) Airbags: Most airbag systems are made up of three basic components.   They are as follows:
The bag:  is constructed of a woven material similar to nylon, which is folded like a parachute.  They are coated with talc like powder that lubricates the air bag material for storage.  After deployment, this powdery dust may contain residue from the chemical reaction, which may cause minor irritation.  The inflation system:  is similar to a solid rocket booster.  This solid material ignites which burns extremely hot and rapidly to create gas.  This action inflates the nitrogen gas (pulsed) via the chemical reaction of sodium azide (Na N3) and potassium nitrate (KNO3), in some older vehicles.The sensor: is an electrical and/or mechanical device, which triggers a firing squib, which activates the inflation system and deploys the air bag.  The electrical sensor uses a tiny accelerometer, which determines certain types of negative acceleration (decelerations).Generally, airbag systems will be deployed at a vehicle that is traveling a range of minimum speeds. Of course, this is subject to many additional factors, such as type of impact, position, delta v (change in speed), and location of the subject vehicle.  However, mechanical sensors (switch) close when mass shifts via the vehicle. It bears mentioning,  that the driver should seat at least 10 inches away from the center of steering wheel to their chest, which contains the airbag.  The proper seating position is the key in order to reduce typical airbag related injuries.
Advanced Airbag Systems – Next Generation
In advanced systems vehicle manufacturers (OEM’s) are using special sensors to differentiate occupants size and/or weight.  This in turn can vary the output of the airbag(s), which in fact makes the system safer. Many OEM’s  use a propriety chemical compound, which they claim to be less toxic, then NaN3 for the inflation system. The airbag itself may have multi-stage compartments, which in fact slows the forward velocity (up to 200 mph / totally time is 20-30 milliseconds; first version) of the bag and has a maximum pressure of  5 psi fully inflated. Some newer vehicles,  are being equipped with  side / curtain, knee, belt(s), seat / door mounted airbags  as well as the required frontal ones. Most side airbags have separate highly compressed air tanks (approx. 3.5K), which make the system potentially dangerous for first responders, if they do not have the proper information.
Headrests Systems – Next Generation
Some newer vehicles have next generation headrests.  In these systems, the headrest(s) actually moments2 in a specific direction for the impending impact, to minimize the person head motion, in order to lower the injury level, e.g. whiplash, etc.Airbag Injury – Potential Dangerous Occupant(s) Equipment
Most parts of a vehicle is either a friend or foe.  When a vehicle is impacted, whether from another vehicle or an object,  there are impact force(s) that occur outside and inside of  the vehicle,  from at least one direction, that can cause injuries, whether from the vehicles own equipment  and/or devices that may react, e.g. seat belts locking- up / tighten, airbag deployment, dashboard components, etc.  As the reactions occur from the impact, the occupants will move in the same and/or opposite direction of travel and/or impact and speed.  Impact forces (energy) and/or airbag(s) striking an occupant that is wearing eyeglasses, can cause additional injuries,  depending on the type of material the lenses. High risk eye wear can be potential dangerous when impacted by impact forces of a vehicle, such as a steering wheel, dashboard, airbag(s).

Figure 1
Drivers can reduce the possibility of  airbag injury (ies) by properly adjust their seat belts and sitting at least 10 inches from the steering wheel, measured from the center of the steering wheel to their chest.  However, if the driver cannot operate the vehicle in a safe and comfortable manner, due to their physical dimensions, pedal extenders should be installed. All occupants can reduce possible eye(s) injuries due to impacting should consider wearing safer eyewear lens material, if available, such as Polycarboate, Trivex, and CR-39; See Figure 1.
2: Movement
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