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Author: sluggishh
Time: 03/29/03 21:00 PST
This is a reply to message no. 10899 by neil moran
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collision problem...
Hello Neil,

Ive got a qn: The equation D = W*L^3 / 3*E*I... Is this the equation for bending, with the upper end free, and the lower end simply supported/fixed?

With regards to finding the unknown stopping distance s for the vehicle, I'm thinking of using s=ut - (at^2)/2
by considering the initial state of the vehicle to be just before impact(u = known initial velocity), and the final state to be at the instantaneous point in time that the vehicle and pole are stuck together at the maximum deflected state of the pole.
However, to find the deceleration (negative acceleration 'a') and s in this eqn, again I require 'time', t, as I've discussed earlier with Rolschwarzm, which I have no means of obtaining.

"Once this is known, divide the KE by this value to give the impact force (kN) of the vehicle"
I'm wondering if ur approach is using the conservation of energy: where the total KE of the vehicle is transmitted to the pole in terms of its stored potential energy at the final deflected state? However Im not sure if this potential energy can be computed as (deflection x impact force)...
This is from the energy point of view. However, if I look at this approach of dividing the KE by deflection to give me the impact force of the vehicle from the point of view of power, u said that
D (deflection)  = KE/impact force, that is, force x distance = energy,
which should be true only if we take time = 1s, is that right?
since force x distance = work done = energy/time
Again the unknown time factor which I hate to involve has popped up!!!
This is why I'm getting all confused. Not know which method I should use to solve this problem...

Thanks for ur comments! U have offered much help. =)


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