Author Topic: Arvins 62" osage design  (Read 2666 times)

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Offline willie

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Re: Arvins 62" osage design
« Reply #75 on: December 30, 2024, 05:15:41 pm »
Any design. Do it in 10 gr increments
Please explain to me in simple terms if this would or would not be useful.

I will plug in some numbers and see what happens, it's easy enough to do. It might be useful to see if the program makes sense to experienced shooters. 

Expecting the dynamic assumptions of the program to work out in real life might be reasonable for a typically stressed bow with a typical arrow at 9 or 10 GPP.
At 3.5 GPP with a highly stresses bow, the program may or may not be as capable.

There are two different parts of Virtualbow outputs, dynamic (moving) and static (stationary).
Dynamic looks at limb return speeds and consequent arrow speeds
Static predicts draweight and bend shapes.

As for the static bending part of the program, I have a little more confidence, as the maths behind bending beams is more established.  So long as the bow acts like a beam, I believe doing something like making the bow longer or shorter, thicker or wider etc. should be relatively consistent.

"so long as the bow acts like a beam" might be pratical at lower stresses, but we are looking to push the stress in the bow until just the point where some damage to the materiel is justified so long as it yields better performance, but just a bit more stress causes diminishing performance. This is more of a grey area that could cause difficulties for the dynamic predictions.




Offline willie

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Re: Arvins 62" osage design
« Reply #76 on: December 30, 2024, 05:19:38 pm »
I have all 4” increments the same on both ends of the bow.

you have been re-shaping the crown to the same "pattern"?  if so can you reconfirm the "best  fit" of the pattern to the diameter of something? 

the number crunchers might be a while longer to work out a set of thicknesses.
« Last Edit: December 30, 2024, 05:32:44 pm by willie »

Offline mmattockx

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Re: Arvins 62" osage design
« Reply #77 on: Today at 12:41:40 pm »
"so long as the bow acts like a beam" might be pratical at lower stresses, but we are looking to push the stress in the bow until just the point where some damage to the materiel is justified so long as it yields better performance, but just a bit more stress causes diminishing performance. This is more of a grey area that could cause difficulties for the dynamic predictions.

willie,

The Euler beam equation holds even at bow limb amounts of deflection as long as shear deflection in the material is small, which it is with the woods we use. I assume all of the various bow design software uses the Euler equation, because the more general Linear Elasticity equation is much harder and more cumbersome to solve and doesn't seem to be necessary.

I can't say how VB does its dynamic analysis, so I don't know if running on the ragged edge of failure affects it or not.


Mark