Main Discussion Area > Bows
Poisson Effect Versus Neutral Plane - A Theory
tom sawyer:
I haven't even progressed as far as determining whther there IS such a thing as a superior cross-section. I'm just noting different stresses that are inherent to greater degrees in certain designs. Nothing I've been talking about, is necessarily pointing to any "best design". All it does is poke some little holes in the arguments of some people who dare to make those kinds of statements.
I've always been in the camp that thought either a mostly rectangular or mildly radiused design would work similarly. The latter having greater aesthetic appeal as well as being slightly easier to accomplish.
I kind of like the idea that you should sort of match the crown of your back, on your belly, maybe leaving the belly slightly flatter than the crown of the back. That puts the NP fairly near the center of the bow. It makes the back do more work which is good since the material is stronger in tension.
SimonUK:
My understanding from the discussion above is that you would need to remove just enough wood from the sides of the belly or back to stop the poisson effect happening. It might not be much wood at all. And the effect on performance might be tiny, but it's a very interesting idea.
jamie:
i think my brain is bleeding. me with hillbilly
Ryano:
:D :D :D :D :D LOL......
Is this primitive archery or rocket science?.... ::)
bobnewboy:
I think I was following this for a while, and then my head started hurting.. :P Then I remembered about the ACS-type section of <whisper>fibreglass limbs - what happens there, and my head went BANG ! :-\ Sorry about that not being primitive ;)
In my case, I feel that nature abhors a perfectly straight line, and also corners, however sharp. Stress of course loves corners, and the sharper the better! So I tend to make the limbs of the few bows which I have done, oval or lenticular in section, and all section transitions via smooth flowing lines. They just seem 'right' when handled and used. I cant explain it further than that, but I guess that for me, this is in the same mindset as 'doing what the wood asks', inasmuch as it is an imprecise science ;D
I need to make some more shavings, and soon.........
//Bob
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