Energy absorption of foam

Hi,
I am faced with a little problem. I have a pyramid (or another shape) in foam. I know its impact compression (stress-strain curve) and as a consequence the energy it
can absorb.
Now, the problem:
I want to absorb a certain amount of energy with a pyramid of foam.
What is the size of the pyramid I can use? How can I easily use the characteristics of the first pyramid for the new one?
Let me know what is your point of view.
Thanks
Jb
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snipped-for-privacy@ifrance.com (JB) wrote:

I have never had to do this kind of problem, but would not a correspondence approach work. My first guess would to be scale the crossectional area up (or down) in proportion to the energy difference provided the deformation in the direction of the principal forces do not vary. But I am not a sress analyst.
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I remember an article in Scientific American quite a few years ago about explosives- They showed foams being used to absorb explosive energy . You may want to find the article (I think it's pre 1999) and take a look at the references. Good luck

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snipped-for-privacy@ifrance.com (JB) wrote in message

Since you are taking the energy absorption characteristics of the foam to be a function of strain only (I would also consider strain rate as another primary variable) then you must scale your pyramids so that strain is conserved. I can't tell you how to do that since it would depend highly on the geometry of the object impacting the foam.
John
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