Fuller'vit

Another example I can think of is those Jerry Cans for gasoline. I heard that the X shape stamped into the sides greatly improved the stability of the can walls. Now in that case material was not removed but rather the X shape was stamped in which I guess would have an effect similar to fluting something. Like corrugated aluminum siding.
 
Take a piece of tin, or brass shim stock. It's floppy. Bend a crease down the center like a pitched roof. Now it's much stiffer. You've increased the cross section. Now instead of .030 thick, it's maybe .500 tall from peak to base depending how far you creased it.

You've essentially created a triangle in the material in the axis of the stress. Rather than the flimsy flat with it's two points or lines of stress, you've added a third and moved them apart 5 or ten times their original difference. That distance is like a lever of support.

I'm not trying to say you can't do this with a fuller as we discussed. If you just move the material into a strategic location like the bend in the shim stock, it has a similar effect.

I'm trying to describe the scale is vastly different. If you take a .200 thick blade and fuller then upset the spine into a short "t" you'll maybe increase it to .250 or .300 at the most. So rather than increasing the cross section by 5 or 10 times, you've only increased it by 25 or 30%.

That's why a tape measure acts so stiff, but the simulated blades with fullers and equal mass only showed a small amount of deflection resistance. So yes, similar effect to creases in sheet steel to prevent oil canning, but at a vastly different scale.

I hadn't even considered the effect that geometry might have on vibration and think that's a very keen insight worth investigating further.
 
kuraki said:
Take a piece of tin, or brass shim stock. It's floppy. Bend a crease down the center like a pitched roof. Now it's much stiffer. You've increased the cross section. Now instead of .030 thick, it's maybe .500 tall from peak to base depending how far you creased it.

You've essentially created a triangle in the material in the axis of the stress. Rather than the flimsy flat with it's two points or lines of stress, you've added a third and moved them apart 5 or ten times their original difference. That distance is like a lever of support.

I'm not trying to say you can't do this with a fuller as we discussed. If you just move the material into a strategic location like the bend in the shim stock, it has a similar effect.

I'm trying to describe the scale is vastly different. If you take a .200 thick blade and fuller then upset the spine into a short "t" you'll maybe increase it to .250 or .300 at the most. So rather than increasing the cross section by 5 or 10 times, you've only increased it by 25 or 30%.

That's why a tape measure acts so stiff, but the simulated blades with fullers and equal mass only showed a small amount of deflection resistance. So yes, similar effect to creases in sheet steel to prevent oil canning, but at a vastly different scale.

I hadn't even considered the effect that geometry might have on vibration and think that's a very keen insight worth investigating further.
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This is what I was trying to describe using the tape measure as an example. Thanks! I think this is why fluted plate armor was so much stronger than non-fluted armor. The ridges add rigidity.
 
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I'm a musician.

Best post in this thread.

Re hammering cymbals is far out.

Rick Marchand said:
Great points, Mecha. I never considered vibration and a fuller's effect on that but it makes sense. I am a drummer and have re-hammered several cymbals to change the sound. Lathe grooves also effect how a cymbal vibrates... so why wouldn't a fuller do the same?... and to a larger degree.

Very cool discussion. Now I want to make more swords!
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Perhaps someone should ask a blade of grass this question?...

yn_sedge2_zpsdwt94xfg.jpg
 
Maybe this have nothing with subject , but ..............I remember years ago when Honda /motorcycle/ change swing arm ,normal one with two arm with one arm swingarm for rear wheel of course .Normal one have two square AL tube with dimension 40x20mm ,I don t remember wall thickness .For new one arm swing arm they use 80X40mm AL tube with same wall thickness as first one . Even today it s hard to believe to me that they have same strenght ............:)
 
I heard the Xs stamped into the walls of jerry cans was to make the walls less flimsy. Isn't oil canning prevented by the X because it makes the walls more ridgid.
 
Lapedog said:
I heard the Xs stamped into the walls of jerry cans was to make the walls less flimsy. Isn't oil canning prevented by the X because it makes the walls more ridgid.
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No one is arguing with that?

Your duct work is creased in an X rather than stamped for the same purpose.
 
Natlek said:
Maybe this have nothing with subject , but ..............I remember years ago when Honda /motorcycle/ change swing arm ,normal one with two arm with one arm swingarm for rear wheel of course .Normal one have two square AL tube with dimension 40x20mm ,I don t remember wall thickness .For new one arm swing arm they use 80X40mm AL tube with same wall thickness as first one . Even today it s hard to believe to me that they have same strenght ............:)
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They never had the same strength but they traded that off for the ease of tire changes in endurance races. Eventually as the horsepower race continued unchecked even bikes that came single sided in stock form got 2 sided swingarms in the race spec and they resorted other mechanical magic when doing a wheel change at Suzuka.

And as a note they would all bend/flex but the dual sided ones would flex with less twist so more consistent feedback to the rider.
 
Mecha Mecha

What would be a realistic moment of torque applied to twisting a sword in in/lbs? I've modeled up a sword to simulate twist and just threw 25 in/lb in but I think that's pretty low?
 
Matthew Gregory said:
All of my fullers add an additional fifteen horsepower with no loss of efficiency.
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That's idiotic Matt. Fullers add fifteen HP per side, so unless you're making single fullered blades it's 30 HP total. And the unit of measure was tacticoolness rating, you have to convert. You twits need to learn basic math. *sigh*
 
kuraki said:
Mecha Mecha

What would be a realistic moment of torque applied to twisting a sword in in/lbs? I've modeled up a sword to simulate twist and just threw 25 in/lb in but I think that's pretty low?
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According to this guy's excellent article, the answer is easily calculated yet pretty much impossible to determine! :D

http://armor.typepad.com/bastardsword/sword_dynamics.pdf

I am NOT good at math, and really don't know how to estimate how big the spike in torque on a sword blade could be, let's say, if one was cutting a huge standing bamboo and made a nasty mis-cut. That energy has to go somewhere. I would guess it could be as high as 100 ft/lbs.

May I ask, is the sword blade in your simulation distally-tapered?

Also, I found this interesting little article scouring around and thought it was worth a read:

http://www.thudscave.com/npaa/articles/howhard.htm

Even though it doesn't really compare to what's going on in a sword blade, this calculator says that a half pound moving at 80 mph translates to just over 100 ft/lbs of force; I'm sure a sword blade can exceed that by a lot. The concentration of power on the thin edge is insane! And the aftershocks run all through the long blade. I have seen a few super slo-mo videos of swords cutting, and they can whip and twist all around in a serpentine fashion although with the naked eye in real-time they appear to stay rigid, similarly to an arrow shaft when the arrow is released.
 
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There is distal taper in the last third of the blade. 28'' long from the guard, .25 at it's thickest, wide fuller tapers with the edge. Just under 2'' wide at the guard to just over 1.5'' before the tip, 1.8 lbs without guard or handle.

I thought you were talking about twist axial to the length of the blade. I agree the forces you mentioned can be incredible.
 
kuraki said:
There is distal taper in the last third of the blade. 28'' long from the guard, .25 at it's thickest, wide fuller tapers with the edge. Just under 2'' wide at the guard to just over 1.5'' before the tip, 1.8 lbs without guard or handle.

I thought you were talking about twist axial to the length of the blade. I agree the forces you mentioned can be incredible.
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Yep, twisting along the length. The hilted end would be held with two hands (like a moving clamp), and let's say that a spot 10" back from the tip is cutting through something relatively hard and tough when it's deflected and twists between the catch-point and the hands. I was thinking that a big fuller could weaken a blade in that regard and more easily take a twist.

It would be fun to test a few real-world examples with a torque wrench, or better, something that impacts the long blade at a bad angle: find out how much it takes to twist the blade. :)
 
Ah gotcha. My biggest problem with realistic simulations is the limited material library. I haven't discovered how, or, if it's possible, to add or customize the materials available to get something that more closely represents hardened blade steel. Everything in there acts like annealed material.
 
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