Armour

[maddox]

Armour

A plywood and steel laminate is very cheap, even compared to hardox. But not nearly as strong.

You can get the steel very cheap from a junkyard. And even 0.8mm Stailess has some good qualities.

But, as Ewan mentiones, the softer and cheaper HDPE or Polypropylene plastics are very suitable to laminate, or even to use as sacrificial armour.
Virtualy unbreakable, lighter and cheaper than Polycarbonate.And resilient.
The wheels from TAN are HDPE, and are meant to be sacrificial,because they cant be build strong enough to withstand everything in the arena.
Now you can imagine our suprise that the wheels did survive more fights than most heavies do in a complete series.

[blazerbotics]

Armour

alot of feathers are turning to polypro instead of polycarb (g3 will be), due to the problems of it shattering/cracking. Polypro is abit more fibrerous and seems to be standing up to the spinners better. Blazer (middle) will be having HDPE armour as we can get it cheap :P
Polypro is also better to work with as it can be heated and bent, you can also melt two bits together.

[maddox]

Armour

The main advantage, according to me, for the softer plastics is that they dont absorb as much force, The disks will cut them, but wont do more damage than a cut.So less inclined to rip complete pannels of the robot in 1 go, or bend the framework.
I hope this theory is correct.

[bugs]

Armour

If i recall correctly, its virtually impossible to glue a thermoplast like HDPE. So a HDPE and steel armour cant be glued and im unsure if a riveted connection would stand much of a chance against disks.

[kaideejee]

Armour

Bolts it is then Theyd likely be ok, though youd be gaining some weight in the connectors I spose...

-- Kev

[maddox]

Armour

Tec7 or simular mastic glue holds it together good enough.
Things to remember then. Degrease the to glue parts perfectly, and give them a rough up with sandpaper, remove dust and so on. Use enough glue and be shure the edges are completely glued.
Now, if you can get the parts under a multi tonnes press let m cure for as long the glue needs.Otherwise, put the parts between 2 sturdy plates ,and pile up every heavy object you can fit on it.yes, if you can get the fridge on it.Do so, and it works even better as the fridge gets loaded with Cider or beer.In that case I come over to help doing this.Especialy the unloading of the mentioned fridge.

[fluppet]

Armour

:-)

Going back a bit, why would you want to harden the wood? Surely its never going to be as hard as the metal, and you want it to be strong, not hard, to support the back - otherwise the first ding in the metal is going to crack it. (Wood glued onto titanium may actually make matters worse, since the titanium is likely to be able to deform and bounce back where the underlying wood would just make it more brittle. Or I could be talking nonsense.)

Ive always been keen on the idea of armour deflecting or avoiding impact energy, rather than trying to absorb it - so the softer plastics sound interesting. Its all very well having 40kJ in a disk, but that only helps if you can transfer that energy into damaging your opponent.

--
Fluppet

[team_ireland]

Armour

Mario i think you have your numbers wrong. Plywood is 0.615kg per dm^3 everything else i agree with.

I use the table here. Duglas Fir rocks.
http://homepages.which.net/~paul.hills/Materials/Materials.htmlhttp://homepages.which.net/~paul.hil...Materials.html

Regards
Ian

[maddox]

Armour

The mass of plywood is different for every different kind of wood and glue used in it. I just took the number I had around.

[woody]

Armour

Density, weight and sizes

The density of plywood is not normally controlled as part of the product specification but is a function of the species of timber used. As such the density can have a wide range, but most construction plywoods have a density in the range of 400kg/m3 to 700kg/m3.
Thus a 2400 x 1200 x 12mm panel could typically weigh between 14kg and 24kg. Some highly compressed, specialist plywoods can have densities in excess of 1000kg/m3 and some have €œbullet resistant€ qualities.

[Guest]

Armour

Whatever type of armour you have the less internal mounting/support the weaker it will be against the impact force part of any blow taken.

Also the shape of the armour is as important and some times more so then what it is made out of.

one last thing to bear in mind what is the surface finish going to be, metals fully harden or case harden, an ablative layer, slippy paint?

Ps. see leg, legs, legs are so great. for more armour talk

[bigsi]

Armour

Just thought Id chip in as we probably have more experience than most in the use of plastics in robots.

Polypropylene - good if you want something stiff but with the kind of impact energies in RWs, it tends to shatter, in a similar manor to polycarbonate.

HDPE - requires almost 10 x the energy density on polypro to shatter. It is softer, but will tend to plasticly deform and absorb impacts / spinning things better than anything Ive come across.

Our drum & outriggers are now made from HDPE.

As someone else mentioned, the way to glue it is with silicone sealant or mastic. In order for a laminate to work as armour from piercing, the layers need a certain degree of relative movement. The mastic provides this.

When our drum was made from Polypro, IronAwe knocked several big holes in it. The same spec of drum made from HDPE has yet to be pierced which kind of speaks for itself. Several things have gouged it, but nothing has got through!

Top this end, we are now building an axe robot, using HDPE for armour - in a way nobody has done before. Providing protection from spinners as well as axes. No laminates, just an intelegent use of the material properties!

Si

[spinnerboy]

Armour

I think we were pretty close to cutting through it in the spinner frenzy at series 7

[bigsi]

Armour

You are not wrong! It cut through about 8mm of the 10mm thickness. We are still running the same drum though.

The only thing to actually pierce the drum was the axe on a robot called ICU (I think), the head of which was like a pencil. Then it only made a 2mm hole!

Si

[mightymouse]

Armour

I have found that a combination of 1.6mm mild steel and 8mm macrolon is virtually impregnable. The only time the lid on Mighty Mouse has been pierced was by Matildas disc.

It has taken a full blow from Thor and sprung back into shape, and 8645t had three free shots with his axe and only cratered the surface.

The 2 materials are not bonded though, they are just bolted (csk m6 screws and nuts internally) this gives an amazing amount of flexibility. I often have to flatten dents out of the steel substructure but the polycarb is only scratched.

I have currently run out of macrolon and am using a sheet of polycarb, no idea of the make or spec, it came from a telephone box. But, although it is slightly more brittle it is no less effective.

Trev