I'm an engineering student from the University of Waterloo. One of our projects this term is to examine how car frames deform under impact, and how to design a certain aspect of a car frame to withstand a crash under certain conditions.

One of my class mates was in contact with the Smart Car manufacturers and they sent back this clip:

Smart Car vs Wall

I don't know about you, but I have a lot more confidence in those little cars.

I am no engineer, but this is what I can guess.

-The smart car is shaped like an egg, and can disperse impact pressure well, and change direction to continue dispersing that energy. So good frame design and it looks good under your research topic.
-It didnt tip over...(where is that picture when you need it? that link got erased last time I checked)
-With that strength, the energy that it does *not* absorb has to be absorbed somewhere else...(fill in the blank)

I have a -bit- more confidence in those little cars, but i wouldnt buy one.

It's hard to tell for sure but I think that if there was a driver, his feet would have been obliterated.

The smart car doesn't weigh very much so there is less energy for the frame to absorb.

Would any other 'normal' car do any better? Possibly.

I’m sure glad that we have people are out there finding better ways to improve the safety standards of vehicles. We have the air bag systems, rear bumper sensors to inform driver's they’re about to back over or hit into an object and the list keeps going. What I want to talk about is a way to protect occupants in a vehicle from G-forces.

Let me go into detail about what I mean. True that in every collision there will be vehicle damage to a certain extent depending on many variables such as speed, impact point, what was hit, etc.

What I think you need to research is how your frame will dissipate the transfer of energy on the occupants at the same time protecting them from being squashed like sardines in a can. This would be the ultimate frame and if you get around to building it…I want a 20% cut of the yearly profit sales.

How much G-Forces are exerted on the body going from the speed of 70 to 0 MPH in 1 second? I can strap myself onto a rocket sled with magnetic braking system and launch myself 0-70 mph in 10 seconds without injury. It’s the G’s experienced when I go from 70 to 0 mph in 1 second. The transfer of energy from the rocket will transfer to my seat, then to my seat belt, then to my inner organs and then my eyeballs will continue out of my head until the energy dies or it hits something.

Just because your body made it through the crash doesn’t mean you survived the pull of instant G’s.

I would definatly purchase a car that keeps body parts from being amputated and at the same time, protecting all the occupants from the sudden G-forces.

Is there anything that can be done to eliminate the G-force push/pull on collision?

I’m guessing that an “anti-gravity field generator is way to sci-fi and out of the question.

If there is any car to get into an accident in, it would be a Benz. Look at Princess Di and crew. Her S-Class hit a concrete abuttment at 160kmh and someone actually survived. A buddy of mine wrecked on the Autobahn at 220kmh rolled a bunch of times and nailed the barrier...he walked away.

The Smart is no different, it is like a rolling cage and has some crumple zones.

No manufactuer has to pass a test like this 112kmh? Of course there will be injuries there.

We test at 50kmh offset, 65km/h into a deformable barrier, 55km/h rearend and side impact of 50km/h the Smart passed with ease.

Good example of this is Dale Earnheart. I thought of him when I saw the clip.

This is some amazing engineering.


But the Acceleration, which you call G forces is what really kills in these cases.
Human body can take only so much of it. but that has nothing to do with the car.

If you guys remember the crash between UofToronto Solar Car and a minivan last year. The fellow suffered almost now external injuries, and that was in a prototype 500lbs solar car. but the impact took his life.

A head on crash at 70, yes your feet and your entire leg has to get ****ed. but that is when you are lucky.

and no, have you seen anycar is a crash like that?!
a HEAD ON at 70MPH. all accidents on normal roads have much lower impact speed. the driver generally brakes for a good while before the moment of impact.

Something like a Civic or a Cavalier or a even a normal Cadillac would do worse than this to its driver.

Wouldn't two cars, each going a mere 35 mph, hitting head on result in the same energy as a 70 mph run into a stationary concrete wall? Doesn't seem unreasonable or uncommon to me.

Now, if only it had more storage space.

I still think it needs more crumple zone. Judging by the video, that's a lot of debris that went flying there. That means alot of energy was disapated, but the dam car still bounced.

yes, if you care about total energy "Wasted"

but each car's body would be absorbing some or like half of it.

if the two cars are the same, once they collide they stop, so it's like the car driving at 35mph and hitting the wall. becuase the wall doesn't quite "move".

but when you hit conceret blcok at 70, you are taking all the force and it is your car that loses speed from 70 to 0 so you experience twice as much acceleration.

I am not good with math in any means.

But you say experience acceleration when hitting a wall. I'snt that decceleration?


OH snap. The car is decelerating and the human body is experiencing acceleration. Is that right?

It's all relative.... literally.

That's correct. What event takes place when you stop a vehicle from moving?

Answer: The vehicle decelerates and the transfer of forward engery goes to your body. Your body is now going through the process of acceleration, until it is stopped by your seat belt or yourself.

I don't remember what the mathamatical formula is for weight multiplication durring sudden excelleration or deceleration, i.e. 100 km/h to 0 km/h in 3 seconds is the same as 120 lbs equaling 360 lbs. - Sorry if this part of the answer is kind of a bit off, but it's a way that I can explain how deceleration can also produce excelleration.

Nathan

The car decelerates, and because you are not moving with respect to the car you HAVE to decelerate too.

However deceleratation is just negative acceleration. Physically, it is the very same thing.


What happens is that the car is moving and you are moving with it.
then the car slows down, and you keep moving, NO you don't really accelerate with respect to the ground.

until the seatbelt grabs you and makes sure that you decelerate with the car as well.


I am not sure what this is supposed to mean but I am not sure if it is right!

The mass is always the same. that is not going to change. However if you are saying that the force is relative to mass AND speed then you are right.
F=MxA
Force excerted on the body is the product of its RATE of acceleration and its mass.

The more you know!

*Insert rainbow noise*

Amin, that is exactly correct. My little skit was an example of what happens to mass when force is applied to it.

I wasn't to sure on how to explain something that I can better understand in my mind than writting it in words. So yes, your formula (force is relative to mass AND speed) is correct.

Wow thats pretty amazing. Neat what a "cage" can do instead of a bunch of tin and crumple zones...

Matt

Sure it can hit a wall and not crumple but what if a transport drives over that little tin bucket... IMO Those things are scary and I wouldn't feel save no matter the tests done while driving around in the snow in canada... like the one I saw last week poor bastard looked horrified driving along the highway in a snow storm LOL!

If a transport was going to drive over you, a DSM isn't going to save you either. I think you would need at least a Sherman tank!

LOL! A trasnport would toss a Smart Car like a little tennis ball where as a DSM is more like a medicine ball since there so damn heavy LOL!

I think they would BOTH end up like a DEFLATED ball....or a pancake, LOL