V8 Supercars 2013

[wobblysauce]

Monety, From memory that is more like the Nascar setup, it just makes it harder to get in and out of the car, so driver changes would need to be tweaked.

[VTRacing]

I'm no metallurgist, but I believe that especially with chromoly the more you weld it the weaker it gets. It is very difficult to weld properly.

You would probably also find that a bar such as you're proposing would not add additional strength overall. You could also imagine that such a bar transferring force to the floor (a very weak area) would just punch through the floor and do nothing.

I've had a chromoly cage break, in part because it wasn't welded with the correct technique, but you really need to limit the heat affected areas if you can. Personally I'm not a fan of chromoly cages in general simply because they're so difficult to do properly. My last two rally cars have had steel cages.

[wobblysauce]

VT, so with your testing of said Steel cages, how did they fair?

[VTRacing]

I'm still here, so good enough.

[Dr. Pain]

My old man use to cart scrap metal and one day he had an old Commodore Cup car that was being scrapped so it went to Sims metal or somewhere like that in Melbourne. It had a steel roll cage. They tried it in their car crusher and the roll cage stopped it dead so they were going to have to gas axe it.

[Exar Kun]

Courtney actually copped a leg fracture:

http://www.speedcafe.com/2013/11/26/per ... ydney-500/" onclick="window.open(this.href);return false;

Still, he did amazingly well. That would have hurt a lot more in the old cars.

[Duke]

Still JC is so lucky to get out of that one with minimal injury.

at the picture in that story... from it you can really see how the roll-cage fared, or didn't as it shows.

[VTRacing]

Welded to add the gusset - I'd suspect that the metal was weakened to a brittle state.

[Jiminee]

Would be an interesting failure to analyse, especially given #22 has taken two really serious hits in the past two race meetings before PI.
I wonder what level of NDT is done following incidents such as the ones Murph had at Bathurst and the Gold Coast? I can not imagine they thoroughly check every weld of the cage as there is simply not enough time and if it is a sub surface defect NDT may not pick it up at all.
I do not suppose we will be given that sort of information but I will ask around and see what I can find. I would hope that the weld design and procedure would be done to minimise damage to the HAZ (heat affected zone) around the weld but that does appear to be where they have failed. Makes you wonder about some of the older V8 Supercars getting around doesn't it?
Could also be that the cage is design to be strongest for a hit by a car on the ground, rather than one off the ground as the #34 car was.

Just thinking and looking at the pic - it may be that the weld affected the material properties and caused the failure, it could also be that the tubes immediately after the gussets are much more vulnerable, so the force has moved along to that cross section and the tubes have failed - which could be solved by extending the gussets all the way from the A pillar to the B pillar.

[VTRacing]

Just thinking and looking at the pic - it may be that the weld affected the material properties and caused the failure, it could also be that the tubes immediately after the gussets are much more vulnerable, so the force has moved along to that cross section and the tubes have failed - which could be solved by extending the gussets all the way from the A pillar to the B pillar.

True, and very good points. I'm certainly not suggesting that I know the answer. Also, it's unreasonable to believe that a cage can survive every possible impact without failing.

I'm sure that all the teams will try and learn from this with their own future cage designs.

The good news is that the cage did its job well enough that Courtney will be back. That might or might not have been the case with the previous V8Supercars.

[wobblysauce]

It also depends on the pressure points.

Eg. If on ground, T-bone you wound have the forces spread over a larger area.

If on ground, 45º impact you wound have the forces spread over a different area.

But this one having a look at the angle and being in the Air, the Wheel and Axle could of been a focus point for a lot of kinetic energy, which it might not of been build for.

Or it could of been like above, and just a sub-fracture of a weakened weld not visible to eyes.

That said it could of been worse if it was not a CotF, with the more centred driving seat. Broken Leg vs just a Fracture.

[w00dsy]

Chrome molly has a lateral strength rating of 2400Nm, but 2200Nm when welded. When braced with side plating like on Courtney's car it has been tested to 3200Nm lateral side loading before breaking in what they call a controlled partial deformation of the fluidities section, which is an area built into the tubing. The impact from Premats car registered 4800Nm of blunt force to approximately 1.8m2 which works out to be 236Nm per square inch of roll cage behind the door. Non athletes legs are rated at only 34Nm of lateral blunt force per square inch but a cyclist like Courtney is usually in the 48-54Nm range. Hence why they have roll cage in that area. As you can see from the numbers a leg is no match for a car going at great speed. In conclusion if there wasn't a roll cage he would be broken quite sufficiently.

[Duke]

Did you randomly grab those number from thin air? HTF do you know this.....???

[w00dsy]

I'm just trying to out wobble the wobbler.

[norbs]

Chrome molly has a lateral strength rating of 2400Nm, but 2200Nm when welded. When braced with side plating like on Courtney's car it has been tested to 3200Nm lateral side loading before breaking in what they call a controlled partial deformation of the fluidities section, which is an area built into the tubing. The impact from Premats car registered 4800Nm of blunt force to approximately 1.8m2 which works out to be 236Nm per square inch of roll cage behind the door. Non athletes legs are rated at only 34Nm of lateral blunt force per square inch but a cyclist like Courtney is usually in the 48-54Nm range. Hence why they have roll cage in that area. As you can see from the numbers a leg is no match for a car going at great speed. In conclusion if there wasn't a roll cage he would be broken quite sufficiently.

LOL.

I knew it was when I read "Chrome molly has a lateral strength rating of 2400Nm". Nm is a torque measurement. Sheer I think is maybe more what you were looking for. I think from memory that is measured in USS(?) Not sure how I remember that. It could be as well.

[w00dsy]

It wasn't supposed to be believable

[VTRacing]

You should have thrown "torsional deflection" in there somewhere.

[Duke]

I'm just trying to out wobble the wobbler.

As I was trying to out the BS artist, which I succeeded in doing.

[wobblysauce]

Norbs, It is SAE.

http://en.wikipedia.org/wiki/41xx_steel" onclick="window.open(this.href);return false;

[norbs]

Norbs, It is SAE.

http://en.wikipedia.org/wiki/41xx_steel" onclick="window.open(this.href);return false;

SAE seems to be a type of steel, not an actual measurement of sheer strength.

Anyone want to guess what decade this discussion could finish?

[Exar Kun]

I'm going to do a VT and say it's "shear" and not "sheer". Although "sheer strength" is still a valid term in the right context.

[VTRacing]

Norbs, It is SAE.

http://en.wikipedia.org/wiki/41xx_steel" onclick="window.open(this.href);return false;

SAE seems to be a type of steel, not an actual measurement of sheer strength.

Anyone want to guess what decade this discussion could finish?

Norbs, it's not SAE.

http://en.wikipedia.org/wiki/Shear_strength" onclick="window.open(this.href);return false;

[norbs]

Norbs, It is SAE.

http://en.wikipedia.org/wiki/41xx_steel" onclick="window.open(this.href);return false;

SAE seems to be a type of steel, not an actual measurement of sheer strength.

Anyone want to guess what decade this discussion could finish?

Norbs, it's not SAE.

http://en.wikipedia.org/wiki/Shear_strength" onclick="window.open(this.href);return false;

Thanks TAG.

Good to see something from school stuck, even if I might not be using it in the right context.

USS: Ultimate Shear Strength, UTS: Ultimate Tensile Strength, SYS: Shear Yield Stress, TYS: Tensile Yield Stress

Oh and Mick... http://www.gingersoftware.com/english-o ... hear-sheer" onclick="window.open(this.href);return false; Thanks

[Jiminee]

SAE = Society for Automotive Engineers right?
As in Formula SAE competition for Universities - which we should remember from LFS.

[VTRacing]

Bingo, Jiminee