Bobfrommaine: Having seen an airbag deploy, I now have even greater respect for the danger faced by first responders. Regarding your comment about review of Newton's Laws: After seeing how little regard some drivers have for reaction and stopping distances, I have unfortunately concluded that some drivers are beyond help, no matter what we try to teach them.
That's a tough one, Ann. I can only back into the answer: Bigger vehicles with more energy absorption area in front don't use knee bags. That said, every vehicle uses driver and front passenger bags, no matter how much crash energy is absorbed by the structure.
Interestingly, we train for airbag deployment during an extrication. Air-bags deploy with significant force and do a good job of protecting the occupants from that ONE impact. Frequently the initial impact is not the one that causes the most injury and the airbags are useless for the second and third impact. Airbags are defined as a supplimentary restraint system; they suppliment the seat-belt! Modern high-end cars actually envelope the occupants in infalted bags; but - big BUT - they do-not-work if the occupant is out of position; leaned over opening the glove box, sitting with the seat leaned far back, etc.. I'm not sure the airbag is the answer to bad driving habits.
bob from maine, you've added an interesting and important perspective to this discussion. I agree about diligent, trained, and I might add awake and alert and not DUI, drivers. OTOH, while hearing about the dangers of accidental airbag deployment I haven't thought of what could happen to rescue personnel in that event.
When I was on the extrication team on my Fire Department we had an opportunity to sit in a vehicle model and have an airbag inflated in our faces. There is no mental method to properly prepare you for the inflation! Seat Belts and Air Bags have made vehicle crashes much more survivable, if only people would use them. Inadvertant deployment of air-bags was and remains a significant danger to Fire Department personnel. Imagine an air-bag inflating while a Fireman is leaning across the passenger seat trying to assist in extricating the driver! Self driving/accident avoiding cars cannot replace a well trained, dilligent driver. An accident, as defined as an unavoidable occurace, very seldom happens. Automobile crashes are mostly caused by driver inattention and poor judgement. A periodic review by drivers of Newton's laws of motion should be mandatory. Thank you, and good night!
Airbags have always been obsolete. It is not just that they are dangerously explosive and expensive, but that they don't work as well as permanent passive devices. Permanent harness or padded restraints not only are cheaper, but work multiple times, and don't have any of the dangers, such at knocking the driver off the steering wheel. A padded frontal restraint could be lowered each time you get into the vehicle, just like on an amusement park ride. That would not only save millions in costs, but tens of thousands of lives. Each seat should have its own padded permanent retraints. It is a matter of time before the public realizes how dangerous air bags really are.
Chuck, thanks for the input. I've been told by the materials manufacturers that newer materials are at least as crash-resistant as metals, and the data I've seen supports that. But it's good to know from the automotive design end of things that that's indeed the case. The second thing I was wondering was if the reduced volume from the earlier metal vehicles meant there needs to be more airbags, which it sounds like you are implying. Is that the case, even though newer vehicles have been redesigned to handle structural loads better?
I worked in the airbag industry for years and was in charge of laser fabric cutting equipment as well as brining in the sewing and module assembly equipment for the late 90s Dodge trucks and other Chrysler vehicles.
the inflators use a small amount of rocket fuel that heats a cylinder of compressed inert gas. This inert gas expands rapidly and a disc is ruptured filling the bag. This minimizes the amount of explosive used in the inflator.
The inflation rate and amount is determined by measuring the impact impulse produced by the cars. Small cars like the Suzuki Samurai at the time had large impulses and required fast, aggressive inflators while the big dodge trucks were softer.
We had to track every part with bar codes, every nut and every rivet and rivet head. Rivets and heads were counted electronically. One time we came up short on one rivet and unloaded and scanned and disassembled an entire truckload to finally find the one rivet folded up in a bag.
The standing dark joke at our company was a riddle "Know what they call a missing rivet on an air bag?" Answer: " A bullet through the head".
We manufactured what I called "pillowcases inflated by hand grenades"
Video of rivets tearing through crash dummies' heads' was always enlightening.
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