Bumper Cars 3

[Dmanley]

Just something I've been thinking about the past while and I can’t seam to find an answer any where.

Why aren't there big springs or shock absorbers in the front of cars to absorb the impact of a crash?
Why isn't there a shock absorber behind the front bumper to help alleviate some of the impact passed onto the passengers?

I've tried all over the net looking for a reason and I don't think I'm asking the right questions!
Is there anybody out there that has seen this and if so could they lead me in the right direction?

Thank you,
Regards,
Derry Manley

 

[chrisvach]

"To me if two cars travelling at 60 kph hit in a 40% offset condition there would be a relative speed of around 120kph, depending on geometry and what not, with a deformable stationary barrier."

It seems to me that the 60 kph test would be adequate to simulate such collision. While the relative speed is 120kph if each car has enough crumple zones to save its passengers in a test collision of 60kph with a stationary concrete wall then both cars would combine their crumple zones to save their passangers in this collision. In other words the change of momentum of each car should be the same as it would have been if that car hit a stationary unflexible barrier at 60kph. (of course here i am assuming the both cars are similar).

The problem is when you crash a "car" that does not have crumple zones, i.e. an SUV. Then the SUVs rigidity would not only hurt the SUV passengers it would hurt the car's passsengers as well.

That is why it seems completely ridiculous to me that the government requires cars to pass tough crash tests but has no such requirements of SUVs. The reasoning behind this that SUVs are classified as "trucks" and thus are "commercial vehicles" and therefore need not be as safe makes no sense whatsoever.

 

[davidinindy]

chrisvach. I think it's the way the SUV's and trucks are used, whether commercial or not. They are often used for heavier-duty tasks, such as towing, off-roading, plowing, etc. (Note: I said often... not always)
And truck frames do, to a lesser extent, have crumple zones.
However, having as substantial crinkle-zone in a truck frame might not withstand the use of a snow plow, or towing a boat.
Smaller, unibody SUV's have more car-like structures because they aren't used like full-sizes.

David

 

[mloew]

This may be helpful:

Bumper Impact Dampers

Best regards,

Matthew Ian Loew


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