Question of vehicular safety 5

[Lion06]

I've been having a discussion with my wife regarding the safety of automobiles. My wife hit a deer today with her car and later made the comment that it's a good thing the car didn't crumple like an accordian. I tried explaining that the crumpling is what makes the car safer to the passenger because it helps to dissipate the energy of the impact as well as decelerates the car at a slower rate (which, in turn, imparts less acceleration and force to the passengers). She is convinced that a car that could make it through a head-on collision with no damage is the safest car to be in (while I told her that is actually the most un-safe car to be in) Let's for argument's sake say a 1970 chevy nova is in a collision with a 2010 toyota camry - she believes the passengers in the nova will make out better. She suggested I come here to pose this question. I already know what the answer is, but I would appreciate if some of you could weigh in.

 

[dgowans]

The danger in an accident with a dear

Paging Dr. Freud...

 

[aafuni]

dgowans,
I think I typed it that way nearly every time and had to correct myself each time.

 

[dgowans]

aafuni,

I hope you took no offense to my remark, none was intended. After the thread turned to how best to extricate StructuralEIT from a tenuous marital situation I found that portion of your reply quite humorous.

 

[MiketheEngineer]

If she is a blonde - like my wife --- GIVE IT UP.. She is right - always right - and DO NOT FORGET that. because it WILL COST you in the long run - or even the short run!!!!!!!!!!

Kind of along the lines of a local "touchless" car wash ad.

She says " IF he won't go touchless - then I will" Hint - hint!!

 

[aafuni]

Yeah dgowans, I was thinking the same thing.

 

[SomptingGuy]

Remind me never to bring this up with the ex-SO. Maybe I can pollute our offspring with the idea...

JMW rocks, as ever.

- Steve

 

[jmw]

Better yet would, Structural, would be if you could be "exposed" as an "incompetent" by some snooty superior engineer (a role playing friend your ongoing argument and chimes in on the wife's side (with all the material Eng-Tips can fake) because that way, he is attacking you.

You could stage this at some suitable wifi hotspot where you take your wife for coffee or something.
You needn't worry about how to steer the conversation around to the topic in question, just the opposite. Try and keep away from it. If your wife is like my wife, and has un unresolved "situation" a nice public place to beat up on her husband is all the prompt she needs to kick off the subject herself.
You might even try shushing her when she gets started.
That works with my wife, nothing more sure to cause and increase in decibels and an intensification of attitude.

She now has either to accept her new champion and in which case you can concede gracefully, or she will resent someone else trashing her man.... she may now attack him which means she has to reverse her position to protect you.

Your friend need not fear long term consequences, he isn't married to her so she can't divorce him, but she may be volatile enough to take drastic "heat of the moment" measures so make sure his PPE includes a stab proof vest.

JMW

http://www.ViscoAnalyser.com

 

[IRstuff]

Someone silly enough to get between an engineer and his wife will probably flail helplessly. KISS principle applies here.

TTFN

FAQ731-376

 

[GregLocock]

zekeman, you'd actually be better off in a massy crumply car every time. Everyone benefits from more crumpliness, you alone benefit from the extra mass.

That's from a simple model using an SDOF model of an energy absorber plus a mass for each car.

Cheers

Greg Locock


New here? Try reading these, they might help FAQ731-376

http://eng-tips.com/market.cfm?

 

[zekeman]

"ekeman, you'd actually be better off in a massy crumply car every time. Everyone benefits from more crumpliness, you alone benefit from the extra mass."

Agreed.

Speaking of safety, how come governments don't mandate testing cars against other cars and trucks at various speeds and angles of collision to get a REAL safety result.

Crashing cars against walls is meaningless when it comes to safety. Obviously , if they tested cars properly and reported the results accurately almost nobody would buy a SMALL car, regardless of the high marks it might receive from its socalled "crash" test.

Do you think governments are more interested in saving oil than saving lives??

 

[GregLocock]

"Speaking of safety, how come governments don't mandate testing cars against other cars and trucks at various speeds and angles of collision to get a REAL safety result.
"
Complexity, cost, reliability, repeatability.

"Crashing cars against walls is meaningless when it comes to safety. Obviously , if they tested cars properly and reported the results accurately almost nobody would buy a SMALL car, regardless of the high marks it might receive from its socalled "crash" test."

I suspect that real customers don't think they'll crash head on into another car. I actually drive a smallish car, for whatever that is worth.

"Do you think governments are more interested in saving oil than saving lives?? "

No, not really. I think the crash testing came about as a way of improving the existing vehicle fleet, rather than starting from the other position, which would be answering "what is the most 'cost' effective way of transporting people"? Where 'cost' includes all aspects of vehicle operation including the cost to society of oil and accidents. I'm pretty sure a Hummer is not usually the amnwer!

Cheers

Greg Locock


New here? Try reading these, they might help FAQ731-376

http://eng-tips.com/market.cfm?

 

[IRstuff]

Actually, the IIHS has been doing its own, non-DOT testing for decades, and with each improvement in the IIHS testing came improvements in both cars and the DOT testing. IIHS was the only proponent of crash testing against parking pillars, and corner crashes.

If you've looked at some of the videos from IIHS testing, you'll be amazed at what even a small car can survive now, compared to 20 yrs ago.

In fact, it used to be that car companies would cry foul about low test scores from IIHS, but they'd quietly fix the vehicles, and pass the following year and trumpet the results.

TTFN

FAQ731-376

 

[Jimwahhh]

I always think about this sort of things in terms of acceleration/deceleration. The human body can only tolerate however much acceleration before whatever happens internally, externally (or when internal things become internal). The whole point of the crumple zone (at least as I think of it) is to elongate the period of time that the change in velocity lasts for and hence the less acceleration on the person. In a rigid car, if the car stops in 0.1s, then you stop in 0.1s (perhaps not all of you though).

Also, the argument for everyone having super crumpley cars is good provided EVERYONE has crumpley cars, otherwise you are going to get the self centered jerks rocking around in rigid cars ruining other peoples cars in accidents relying on their crumple zones, until of course they hit another rigid car or something solid.

 

[IRstuff]

That point is q bit moot, since all cars have to pass DOT tests, and most cars get tested by IIHS. In both instances, getting a passing grade requires the car to have crumple zones. Otherwise, they would get crappy results in the testing.

TTFN

FAQ731-376

 

[Tmoose]

In the early 70s my cousin whacked a deer while driving my Grandma's Porsche 911 and he was OK but the upper portion of the car was bent badly. Maybe totaled.

I think a vehicle designed with Moose crash tests in mind may be in order. That meant Volvo or SAAB. No idea what it means today.

Supposedly 90 accidents involving cloven footed animals occur in Sweden every day. Stout A-pillars, etc.

http://www.vti.se/EPiBrowser/Publikationer/S342A.pdf

 

[Yagonyonok]

Up here in Alaska, we get quite a few moose on the roads every winter. They actually have signs with a running total for the year, as a reminder to slow down and watch out. It takes a pretty big vehicle to do anything but send the moose into the wind shield, so the crumple zone doesn't help much with it.

Engineering is the art of modelling materials we do not wholly understand, into shapes we cannot precisely analyse so as to withstand forces we cannot properly assess, in such a way that the public has no reason to suspect the extent of our ignorance.
-A R Dykes

 

[321GO]

I guess she's right, if see had no internal organs at all.

 

[moon161]

Flowers.

 

[kacarrol]

rmw,

While I completely agree trying to argue technical matters with a non-technical individual is clearly a futile battle, I sincerely hope that your second argument was a joke.
____________________________________________________
StructuralEIT,

Non-technical people can make me develop an eye twitch within seconds of conversation. It probably would be best to let this one go with your wife; I've had to bite my tongue on many subjects over the years for the betterment of a relationship.


K

 

[jmw]

Some people, it seems, need to have two or three wives before they learn these lessons.

Question: Why is divorce always so expensive?
Answer: Because it's worth it.
Caveat: But only if you learn from your mistakes.

E.g. you may try to explain how the central heating system works to your first wife (see Sompting Guy's cryptic above) but you should know better than to try and explain to the next wife. Just accept that when you are hot, she will be cold and will crank the heating up to the highest setting and forget it.
When you are cold she will open the windows and let the snow in, still with the heating on full blast.

I was at a refinery in Southern Siberia when the temperature was about 30C below. Getting fed up with freezing in the pump room (a potential death trap due to all the exposed high voltage switch gear in there) I headed for the control room.
This was a couple of hundred meters away and the doors and windows were wide open. You could feel the heat roiling out from several paces away.

To be fair, it may well have been that they had no control over the massive steam pipes running through the control room but I suspect it had something to do with the fact that the control room seemed to be entirely staffed by large women.



JMW

http://www.ViscoAnalyser.com