Airbag Deployment/Safety

[pkopic]

I had a question/concern regarding the deployment of airbags, and the general safety of airbags. We all know that children should not sit in the front passenger seat if the vehicle is equipped with airbags because the airbag could be deadly to the occupant. If airbags are not safe for kids are safe for smaller females (ie. ~ 110lb 5’5 ~ 5-10 percentile)? What minimum velocity and/or deceleration (ie. -G force) is required to actuate the FWD airbags? With what velocity is the airbag eployed? Does anyone have any more info on airbag safety or could someone point me to a good source?

Cheers,

 

[Cdykster]

I do know that many of the automotive companies are now coming out with smart air-bag sensor systems that weigh the occupant and also determine if the occupant is fully reclined or leaning forwards. Based on that input data, the airbag is inflated gently, with medium speed or with high speed. The stories we hear about children getting killed by air-bags may soon disappear

 

[GregLocock]

I disagree with the following phrase "If airbags are not safe for kids ..."

I think the jury is (literally) out on whether /on balance/ older airbags are unsafe for smaller passengers. Media hysteria is no substitute for statistics.

I agree the newer systems will be better.

Crash pulse at the sensor is around 80g but varies a lot for different cars. I don't know about speeds, I thought they went off even if the car is stationary. If you are looking for the acceleration of the occupant as he/she kisses the airbag then I haven't got a figure. Probably 10g or so. The real killer is skull rotation, I have no idea whether that is measured properly, routinely, yet.

Anyway, fit and wear 3 point seatbelts.






Cheers

Greg Locock

 

[GregLocock]

As to links try

http://www.autoliv.com,

and google, there is heaps of stuff around. Here's a relevant paper.

Annu Proc Assoc Adv Automot Med 2002;46:387-409

The 5(th) percentile dummy in a 56 kmph full-frontal barrier crash test.

Beuse NM, Hollowell WT, Summers L, Morgan RM, Park BT, Rockwell TE, Swanson JL.

National Highway Traffic Safety Administration.

In 1998, the National Highway Traffic Safety Administration (NHTSA) tested the 5(th) percentile dummy and the 50(th) percentile dummy in 48 KMPH (30 MPH) belted full-frontal crash tests. From these tests, it was concluded that the 5(th) percentile dummy experienced increased injury measures to the neck and tibia compared to the 50(th) percentile dummy when crashed in the same vehicle. In 2001, the agency conducted ten belted 56 KMPH (35 MPH) frontal vehicle crash tests using the 5(th) percentile dummy. This paper summarizes the results and findings of those tests. The results indicate that the 5(th) percentile dummy is a robust and very durable dummy, which could be used as a tool for safety information. The testing also showed that, for some vehicles, the 5(th) percentile dummy incurred greater injury measures than the 50(th) percentile dummy tested in the same vehicle, particularly for the neck and the lower extremities. The average Nij reading for the 5(th) percentile driver dummy was 0.82, while for the 50(th) percentile driver dummy, the average Nij reading was 0.39. Also, the average normalized neck tension reading for the 5(th) percentile driver dummy was 0.70, whereas it was 0.41 for the 50(th) percentile driver dummy for the vehicles of this test series. Average normalized neck tension readings for the 5(th) percentile passenger dummy were 0.40, whereas 0.28 was the average normalized reading for the 50(th) percentile passenger dummy in the vehicles tested. For the 5(th) percentile driver, all but three vehicles exceed one of the four indices for the tibia, whereas only four vehicles exceeded one of these indices for the 50(th) percentile driver. Finally, the testing revealed the need for different stature dummies to ensure equal protection for all occupants.

PMID: 12361521 [PubMed - indexed for MEDLINE] Cheers

Greg Locock

 

[GregLocock]

Also there are obviously many SAE papers on this.

SAE 980640
Does Stature Influence Driver Injuries in Airbag Deployment
Crashes?--Analysis of UMTRI Crash Investigations
Donald F. Huelke
University of Michigan Transportation Research Institute
Copyright © 1998 Society of Automotive Engineers, Inc.
ABSTRACT
At the University of Michigan Transportation Research
Institute (UMTRI), 763 crashes involving steering wheel
airbag deployments have been investigated in detail (as
of 12/1/97). A subset of only frontal crashes, in which the
steering wheel airbag deployed, and stature was known,
was formed (636 drivers). In these crashes there were
201 "short" stature drivers, 165 cm or less in height (32%
of all drivers). The vast majority of all drivers were lap-shoulder
belted. Of these drivers, 69% sustained no
injuries or an AIS-1 level injury. Of the shorter drivers
there were 40 MAIS-2 level injuries and 15 who survived
with an MAIS injury level of 3, 4, or 5. These higher level
injuries were usually found in only one body area. Details
of the injury locations and contacts are presented. Data
on the taller drivers (435) were similarly tabulated. Of the
taller drivers (> 168 cm), 74% had a MAIS-0 or 1 level
injury. Of taller drivers with the MAIS-3, 4 or 5 injuries,
the majority (70%) had such injuries unrelated to the
deployment of the airbag. Of all the MAIS-2+ injured
drivers, short or tall, 57% had such injuries unrelated to
airbag deployments. The lower extremity was the body
area most often involved, followed by the brain and upper
extremity injuries.

So as I said before, if you are wearing a 3 point belt then even a shortie is pretty safe.


Cheers

Greg Locock

 

[gbent]

Airbag deployment velosity is often listed around 250-265 MPH for the sodium azide units. I don't know about some of the newer activators. Sodium azide seems to be on it's way out at least in part due to the highly poisionous nature of the unfired propellant.

What types of inflators are being used with the variable force bags? Does anyone know about the repairability of the compressed gas inflators?

 

[patprimmer]

I must say, I see a real moral issue here.

I personally am being forced to downgrade my personal safty and suffer increased expense, because laws are applied to me as well as to people who do not wear or do not correctly adjust their seat belts.

My personal first choice was a 4 point harness, but it does not meet Australian design rules for a street registered car, as it is not a retractor design.

Also, the airbag in my current car does not allow me to fit my leather rim steering wheel, and I consequently suffer a loss of comfort and grip. Further to this I need to reposition my arms to suit the airbag, rather than to maintain maximum control.

All this is forced on me because others do not wear or adjust their seatbelts correctly, ie tight. That is considerably tighter than a retractor design provides. Regards
pat

 

[brad]

Patprimmer-
Total agreement.

I've been aware of this fact for years, and in my view this is a morally reprehensible outcome of the US's "protect the idiot" attitude. I don't advocate shooting people who don't wear seatbelts, but come on--it's anti-Darwinism to require that a 95-percentile males who don't wear their seatbelts be saved if it's at the expense of anybody who IS wearing their seatbelts. "We're trading off 100 deaths for one or two" is the logic; however those 100 hundred combined deserve this protection less than the one who is wearing her seatbelt (but happens to be a 5-percentile female).

Off my soapbox
Brad

 

[patprimmer]

Greg

Does that mean that in Aus, they test and design airbags for a driver posture of straight ahead, 10 to 2 relaxed situation, or various likely postures while trying to regain control, or avoid colision.
Sorry if the question is a bit provocative, but I have had a background of applied science, and have had many issues, re reproducability and interpretation of data from lab to real world vs reproducability of data from lab to lab Regards
pat

 

[GregLocock]

<Pat> For the certification tests posture is fixed. Anything else is research. We also have internal standards that are more rigorous, and if we fail them then we have to justify why we should go ahead.

I agree with your doubts about repeatability - getting a new body/chassis/SRS etc through crash certification takes about 50 crashes, which at a million a shot (including cost of protos) is prohibitive. One of the reasons we need so many is that variabiality has to be measured.





Cheers

Greg Locock

 

[patprimmer]

At $50,000,000 per new model test regime, I guess we should be carefull what we wish for, in case we get it.

I would hope the prototypes might be used for other non destructive tests before crash testing.

I would hope that some aquired knowledge from previous models, especially where ther is little change, could be presumed to still apply, with minimal testing simply for reconfirmation, then the freed up budget might be better spent with more exploratory tests.

I guess from my experience with NICNAS, Workcover and various education depts, that government authorities are not that progressive. Regards
pat

 

[GregLocock]

Sure, I was thinking about one particular program when I said 50 prototypes. For a reasonably significant change to a known vehicle I guess you'd be looking at maybe 5 full crashes. Our prototypes are a lot cheaper now as well.

There isn't time to get much other useful work out of a crash car, since their results are likely to have the most impact (sorry) on everybody else, they have to get priority.

You are right, getting the government to change the regs is a long and tedious job. There is a move to harmonise automotive legislation around the world, it has been going for five years with no apparent outcome!

Cheers

Greg Locock

 

[patprimmer]

Greg
I think it is called non tarrif barriers. Regards
pat