So I’m not English speaker so forgive me if I use the wrong terms. Why do barrels or casks (dunno the right term) have more concentrated hoops towards the end and not at the center?
I think it is about pressure but I do not fully understand why? Is this because when they are not placed on the side the highest pressure is below?
You can also explain like I’m 10 if you fin dir easier.
Thnak you!!!
In: 30
So the sides of those kinds of barrels are made from staves, those long vertical pieces of wood, and the staves are originally straight pieces of wood that are bent into a curve when being made into a barrel. They are under tension in the barrel; on the ends, the hoops hold the staves inward. The center parts of the staves don’t collapse inwards because they all hold each other, kind of like all the pieces of a stone arch.
So because of this, on the top and bottom (ends), there is a lot of outward force that the hoops need to hold, but in the middle the hoops only need to keep the staves from hopping beside each other and collapsing the “arch”, so they aren’t holding as much outward force.
Here is a short video showing the basics of barrel construction; it doesn’t directly answer your question, but with my comment it should help. https://youtu.be/X56uglze1G0?si=uI8QbAErCLSNkKvL
The pressure on the staves is greater as you move towards the ends of the barrel. It is as simple as that.
Interesting side note. You can tell the REALLY old barrels by the # of hoops. IF a barrel has 6 hoops, it is most likely pre-WW2 (and yes, I have seem them). They reduced the number to 4 as part of the rationing during the war.
Barrels are designed to be rolled so you do not want a metal band in the middle.
Then consider how the wood bends, the wooden staves are straight when you make them. You need to press and bend the end part a lot more than the middle so you need to put the metal hops there to force the wood together, No band is needed in the middle
Look at [https://youtu.be/TZwUIUNTo8A?t=231](https://youtu.be/TZwUIUNTo8A?t=231) where you see it with half of the band on a later how it is compressed into the right shape with the hoops, There is simply not need to have one in the middle
Pressure in materials is highest in corners.
Stuff in the barrel won’t break the planks of the barrel by breaking the planks. It pushes on all planks inside the barrel trying to push them away from eachother.
The circle shaped top and bottom only prevent planks from going inside, it basically makes the shape and makes it watertight.
So if stuff inside the barrel wants to push the planks to the outside it pushes everywhere, but if planks get lose from the top and bottom the barrel is broken. So here you put a ring around the planks so the planks can’t move to the outside.
Also they make the planks curved. It makes the corners more round.But another thing barrels have to do beside keeping stuff inside is they have to be stackable.
If barrel is on the side and other barrels get put ontop of it, the weight wants to make the curved planks straight, so they want push themselfs away from the top/bottom but the rings keeps them together.
If barrel is normal placed and gets other barrels ontop of it, the weight wants to make the planks more curved. Planks can’t move to the inside because of the top and bottom.
But because planks get more curved, tension gets increased like a bow. So planks want to push to the outside more and get lose from the top or bottom. This is prevented by the rings.
if you tie a bundle of sticks by the middle alone, that becomes a pivoting and bending around point. If you tie by the ends, they cancel each other in terms of bend and pivoting, and the middle can’t move if the ends can’t either, so reinforcing the middle doesn’t help all that much You can try this yourself even.
There is more than this happening on a barrel and bands on ends help with those too, but this is the basis of it, you always need to secure the ends and that automatically improves the stability of the center.
Barrels bulge at the middle not because of a force in the barrel pushing out. There’s a bulge in the middle because the pieces of wood are being pulled together at the ends. The ties at the ends of the barrel are what holds a barrel together, and it has to be tight enough to maintain a water-tight seal. That takes a good deal of force, which is why there are multiple rings holding everything in place.
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