Stresses on a bow, reflex and deflex, wood capabilities

[RyanY]

I think you're starting to get it. The thinner bow would certainly be under more stress because there is less wood overall to do the work. While most of the strain is on the back and belly surface, the inside part of the bow limb also contributes just to an exponentially lesser degree as you approach the neutral plane.

[beast]

Ok everyone i have it all figured out.
the reason why the reflexed bows with the amae width as a normal bow is under more stress is because though the work dis dealing with the same amount of force, it is being distributed through a thinner limb, so less material is doing proportionally more work.

[beast]

 thanks ryan and everyone else who responded.
this helped a lot.
but lol it wont stop me wanting to make reflexed limbs.
so now if I want a reflexed bow to be under the same stress, though the same draw weight it would have to be wider and or longer

[beast]

i said work up there, i meant wood. the spell check is annoying

[willie]

Ok everyone i have it all figured out.
the reason why the reflexed bows with the amae width as a normal bow is under more stress is because though the work dis dealing with the same amount of force, it is being distributed through a thinner limb, so less material is doing proportionally more work.

the stress on any bent limb varies from the surface to the center of the limb. it is highest at the front and back and least towards the center.

any design that pushes the materiel to it's working limit, will be limited by the stress at the back or belly (usually the belly for most woods)

[beast]

right. so i know what happens when a bow's back gets stressed too much, the fibers rip apart.
but what happens when a wood fails in compression?

[RyanY]

The cells or fibers get crushed. Pushed past the point where they can return to their original shape. Plastic deformation.

[Digital Caveman]

I think that happens a bit on the back to, most materials will not return to their original shape if you stretch them to far, even if they are not broken.  Total compression failure is what happens with frets and chrysals.

[PatM]

Wood is not considered a ductile material.

[Digital Caveman]

It's a matter of degree.

[Badger]

  Several years ag I built an osage bow deflex reflex design maybe 3 1/2" reflex. No matter what I did even on the best bows I would get a little bit if set. So I thought just for the hell of it I will go super wide like 2 1/2" to see if I could get close to zero set. The bow came out good but what was interesting was that the mass came out slightly lighter than a typical bow of 1 3/8 width even though it was almost double the width. The reason the mass came out so low was because it didn't adhere to the beam theory we often apply to bows. Twice as ide would normally mean about 25% thinner in thickness. Instead it was almost 50% thinner. Only thing that could explain this is that we are doing more damage to the wood than we think we are or even pick up on when we measure set.

[RyanY]

Steve, I don’t think I ever asked but did that wider bow shoot faster than the ones taking set?

[PatM]

I believe  it did briefly.

[Badger]

 Pat, the one you are thinking of here was a super recurve. It shot fast for a few shots but broke down quickly. The one i am talking about here I don't think I ever properly tested and ended up giving it away but I know it was a good shooter it took almost no set at all.

[RyanY]

If we can make bows wider with less mass and set is there any reason we shouldn’t be making wider bows from a performance standpoint?