Armour question

[plargen]

just wandering if 3mm mild steel will hold against a featherweight axe or would i need something thicker

[JammyONE]

Re: Armour question

Yes it will, I have 3mm mild steel on top of Mr Pink, didn't even mark it.

I had a cheap 4mm aluminium plate top from ebay before it got bent, if the axe hit's the same place 3 or 4 times, then it may have gone through it.

[PJ-27]

Re: Armour question

LH almost got through the 2mm Ti on top of BitzaMk2 with a single blow to give you some comparison.
There's more to armour than thickness and material type though.

[Liftoff]

Re: Armour question

depends on the type of steel I think. There's a general misconception that titanium is stronger than steel - which is not totally correct - titanium and mild steel have almost identical properties when it comes to strength and hardness, but its approx 50% lighter.
Titanium alloys such as the 6Al4V are much better, but so are certain grades of steel, I was thinking about some ground flat stock (tool steel) which is harder than titanium but expensive and a bit heavy

[plargen]

Re: Armour question

well i was going to make a shell a bit like bigger brothers, various shapes welded together at different angle to re enforce the structure and then if i had any weight left i was thinking of putting poly carbonate or HDPE in strategic places

[RobotExtreme]

Re: Armour question

I use 5mm of Aluminium, alloy 5058.

In this combate, against the probably most powerful FW axe. I suffered many blows, the top of my robot don't had major damages.

You can see: http://www.youtube.com/watch?v=R_ZjrOsiHso

[plargen]

Re: Armour question

i would go for aluminium but ive only ever tig welded it before i know i can use mig and stick to weld it but its suppose to be a pain

[plargen]

Re: Armour question

does anyone know if 6mm thick t6 aluminium would hold up against a spinner

it would be bolted to the structure and at a slight angle

[Eventorizon]

Re: Armour question

The way I see it is that the material is only half the story.

Going back to Bitza 2 vs Little hitter, I know that the metal on the top is only supported at the edges. What I suspect is happening is that as the material isn't held stiff and can bend it is wasting some of little hitters energy and as a result, not getting punctured.

Conker 2 is designed in a similar way. The 2mm Ti armour could probably get punctured by little hitter or NST but it is mounted on a layer of HDPE and has rubber washers between itself and the chassis, giving it some room to flex.

As for the Aluminium, Solidworks 2013 give the following properties for various T6 Alu's...

4032-T6 : Yield Strength: 315MPa, Tensile Strength: 380MPa, Shear Modulus: 26GPa, Mass: 2680Kg/m^2
6061-T6 : Yield Strength: 275MPa, Tensile Strength: 310MPa, Shear Modulus: 26GPa, Mass: 2600Kg/m^2
6063-T6 : Yield Strength: 215MPa, Tensile Strength: 240MPa, Shear Modulus: 25.8GPa, Mass: 2700Kg/m^2
7075-T6 : Yield Strength: 505MPa, Tensile Strength: 570MPa, Shear Modulus: 26GPa, Mass: 2810Kg/m^2

As you can see the Alloy has a massive effect on the strength. 7075 Is typically for high strength engineering where as 4032 is used for high tolerance applications but is pretty useless structurally. .

If you want to stop spinners you could welding up a cheap steel shell and then having it Nitrided or case hardened. Each has its own benefits. I am sure someone on the forum could do it for you on the cheap; we have our fingers in many pies after all!

[Danjr1]

Re: Armour question

If you want to stop spinners you could welding up a cheap steel shell and then having it Nitrided or case hardened. Each has its own benefits. I am sure someone on the forum could do it for you on the cheap; we have our fingers in many pies after all!

If you do find someone who can do either for cheap, please let me know! Would be interested in getting a frame hardened.

[RogueTwoRobots]

Re: Armour question

If using Bitza as an example, don't forget that Bitza Mk.1's uber-thin dishwasher material front scoop stood up to and beat Little Spinner 4 at the 2011 UK Champs

But as Alex has expanded on, how you mount the armour is just as important as the armour material when it comes to spinner attacks.

[PJ-27]

Re: Armour question

LS4 did blast a 25mm hole in it though (with a blunt edge) but the damage was superficial, curved and angled edges are the best armour.