Re: RE:crash tests..uh oh.

["Robert Dalton" <rpdalton@onebox.com>]

It should be possible to improve a car's crash
safety.  My VW Westfalias which are fun for camping
and trips, desperately need such an improvement.
 Extra crush zone should improve any vehicle's
crash safety.  I sometimes see 4X4 vehicles with
their bush catcher pipes in the front for off road
use (to protect the radiator),  These bush/cow
catchers at the front of a vehicle could be designed
to provide extra crush space.  They probably would
make the vehicle look more rugged or sporty as
well.  Any mechanical designers out there who could
advise how to design this bush catcher for enhanced
vehicle safety?

-- 
Robert Dalton
rpdalton@onebox.com - email
(703) 234-3969 x1020 - voicemail/fax



---- Matthew Caprio <cap29100@flash.net> wrote:
> At 09:21 AM 12/13/99 -0600, you wrote:
> >Lawrence C Leung said:
> >
> >		... Be aware that two cars travelling
> towards each other,
> >each at 30 MPH is an extremely severe collision,
> visually, it would LOOK
> >like driving into a parked car while you were
> doing 60 MPH, brakes OFF. 
> >
> >I believe physics shows us that 2 cars head-on
> each going 30mph is not the
> >same as 1 car going 60 into a parked car.  Each
> car absorbs 30mph, not 1
> >absorbing none (unless it is a semi-truck) and
> the other car absorbing all.
> >Small point, but a common misconception.  
> 
> 
> Hey Guys,
> 
> Believe it or not, it gets even a little more
> complicated than this.  With
> the risk of this starting to sound like the T*rsen
> list...
> 
> Yes, there is more energy stored in the one car
> going 60, than in two cars
> going 30.... that's because the energy stored
> in a moving mass increases by
> the square of the speed, (but mass only to the
> first power).  So, in
> actuality, the single car going 60 has twice
> as much energy stored up as
> the pair of cars going 30...
> 
> And, both cars absorb the same amount, no matter
> how fast either one is going.
> 
> BUT, it's not just the amount of stored energy
> which is dissipated which
> determines the results of a crash-- it's also
> the amount of time in which
> this energy is dissipated (dissipated power).
>  For example, if you are
> going 60 mph and you put the car in neutral,
> you are hitting the wind, and
> letting the impact with the wind *slowly* decelerate
> you to (almost) zero.
> You would experience all of that energy being
> dissipated, but over a longer
> time, so there would be no impact on your health...
> 
> So, the point is, that if you send two 30 mph
> cars into eachother head on,
> the two cars will stop in a VERY short period
> of time (ie high dissipated
> power).  This is because the two cars will end
> up stopping right about
> where they hit-- they won't go sliding together
> in either direction, since
> they are the same mass.
> 
> However, in the case of the car travelling at
> 60 into a stopped car (twice
> the energy of the two cars travelling at 30 needing
> to be dissipated), the
> collision will start to accelerate the stopped
> car, and the car travelling
> at 60 will end up coming to rest somewhere far
> down the street from the
> initial point of impact...
> 
> But, it's the initial impact that counts, and
> computing it requires
> specific knowledge of the structure, materials
> etc., so I don't have the
> means or reason to try and compute it right now.
> 
> The point is that the two scenarios aren't the
> same (two cars at 30, one
> car at 60).  But to determine which one is worse
> is not that simple (but
> it's probably the single car going 60).
> 
> In any event, if you are inside any of these
> cars, brake and steer, and you
> won't have to find out.
> 
> 
> 
> 

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