[Gerald Fa.]

How much does flutes and ridges give strength to armor and metals? I ask because I been told it can go up to about twice the strength of the steel or metal depending the about of flutes and ridges it has, and as low as about 1/5th stronger if it has very little. Can anyone tell me if this is true or how much stronger the metal gets?





We also see it on Roman helmets.


My point is we see it everywhere and is applied on it when it can be. We also see it in tin cans as well as bottle waters.







Does this look familiar?
This is not plate armor but I cannot help it but notice how the concept is more or less the same to European plate armor.








This also shows that the flutes and ridges itself can help in the defecting of attacks; I am assuming that this has a similar effect in Gothic and Maximilian armors as well.

What are your thoughts people?

Thanks!

[Mario M.]

You are comparing stuff that is not really connected.

Fluting on plate armor was done for entirely different reasons than on bottles and tanks

I am not sure about how it effects penetration from projectiles or even thrusts, but, from my understanding, it is done because of structural dynamics of surfaces.

Meaning, it's main purpose is to prevent the surface of the plate from caving in or denting from a strike.

[Jared Smith]

They actually "could" all be very related. Fluting on armor should add stiffness with less weight than simply increasing material thickness. If it is plain mild steel, the fluting or cold working could increase ultimate strength as well. I doubt the ridges in the bottles were formed cold though. Polymers and low carbon metals can actually be stiffened, and actually have strength increases from cold working.
https://www.nde-ed.org/EducationResources/CommunityCollege/Materials/Structure/strengthening.htm

[T. Kew]

The short answer here is it's much the same principle as an I-beam (or a H-beam, which is clearer in this font): fluting something gives it more stiffness for its weight, because it is effectively thicker.

So corrugated iron is very stiff in the direction it's been fluted, because it's effectively an inch thick, instead of being merely a few millimetres thick.

This will not make it as sturdy as something which is actually that thick and solid, but it does keep the mass down.

In general, for a given weight you'll make a stronger structure by having it be fluted or corrugated. For a given thickness, you'll make a stronger structure by having it be solid and uniformly that thickness. Of course, the limiting factor for armour is normally weight, which is why fluting can be quite beneficial as a design feature.

This is also why bottles are typically fluted/not just cylinders - they're much stronger and more crush resistant, for no additional mass. To experiment with this, go find a couple of plastic bottles at your local store: one should have walls as straight as possible, and one should have a more complex shape with indentations and so on. Once emptied, you should find the former is much easier to crush in.

[Michael Beeching]

T. Kew has stated this very efficiently.

On a more technical level, what is happening with flutes & corregations is the material's second moment of area is being increased in one or more plane in 3D space. The greater the second moment of area, the more resistive to fexure an object is.

I want to comment that T. Kew has brought up a very significant point: that solid objects are in theory stronger than corregated or fluted ones - the reason we want to avoid making such objects when possible is that the gain in mass is often unjustified in comparison to the strength gained by using such a solid object. This general understanding of things, which is more common than you think, has ironically lead to the misconception that fullers and I-beams are somehow stronger than solid pieces of a given material. As already stated, the fullers and the I-beams just let the thickness be retained while reducing the mass - the extra strength from the mass would be a marginal factor in comparison to the weight gain.

Now, one thing which might happen with a fuller or a flute in an object is some additional stress hardening when flexed. This could make the lighter object stronger than a solid one to a degree, at the price of material fatigue and increased brittleness.

[Timo Nieminen]

[Bob Haynes]

[Luka Borscak]