Composite Impact Attenuator

[Oliver King]

Hello,
Im currently in the process of designing a carbon fibre impact attenuator for our 2013 car. It would be good if anyone could share some advice on past experience i.e. how many layers they used? and what they found by testing different layups including materials such as kevlar and Flexicore?

Any help appreciated

[Dewi Griffiths]

Hey Oliver,

Were very interested in this subject too. But I don't think many other teams are that happy sharing exactly how they did it.

I would recommend looking at Oxford Brookes facebook page since they add a lot of build pictures. From memory there are pictures showing the layup and a slow-mo video of the crashing. Maybe you can get some clues from these!

[RaceCatt69]

[Tonks]

Adelaide ran with a carbon fibre IA in 2010 + 2011. I don't know the details about it unfortunately.

There is a video on our fb page if that helps you at all?

[Dewi Griffiths]

From what I said earlier

http://www.facebook.com/photo....00458&type=2&theater

[JWard]

Wisconsin have a really simple carbon IA made of 4 tubes secured together with a carbon strap. I couldn't tell you if these are stock carbon tubes, or layed up themselves. (I imagine laid up in house as I can't imagine many uses for them as a commercial product?) Their website has a fairly detailed build gallery for the 211.

[Oliver King]

Thanks for the help! slowly getting an idea about how to go about this.
To me it looks like Brookes constructed their nose cone from a number of 3" carbon fibre strips

http://www.youtube.com/watch?v=suhCBcKhbis
This video shows the manufacture of an F1 nose cone and they use aluminium flexicore as a core material.

I guess there are many ways to go about this.

One idea i have is to use polyester resin rather than epoxy due to its brittle nature

[JWard]

I have a recollection of a GFR nosecone layup picture (or video?), they appeared to use some thin (looked less than 3/4" if not 1/2") core on atleast one of their test lay ups. I remember seeing something to do with attachment points in the 'coque at the same time if that helps. I imagine either facebook or possibly in their docu?

[Nath_01]

Hi,
Deakin University found a loop hole in the rules for 2010 that allowed us to utilize a single carbon fiber tube, mounted to the mandated anti-intrusion plate with a crush initiator;



It was wrapped with a carbon skin that wasn't structural and crushed;


It allowed us to save 1.78 Kg's out of the IA compared to our old design but the rules for 2011 were change specifically to outlaw this type of IA.
Just thought i would share so as NOT to recommend it for the current series.

It was worth all the effort to see the look on the technical inspectors face at competition, when i removed the carbon skin his eyes buldged!
Also got credit for it in the design event when the judge said "i see what you have done here.....and i like it"!!

Just thought i would re-live some memories...
Best of luck,
Nath

[Tom W]

@Nath, I considered doing exactly that for our car in 2010 but assumed that they would not pass a car that did that through tech inspection on the basis of the 'intent of the rule' rule...

@ Oliver or anybody else who happens to be interested here is my write up on the topic: https://www.dropbox.com/s/60td.../z3159015_Thesis.pdf

The cored concept is probably worth investigating as a way around the problem of buckling that you will almost certainly have with the very thin walls that are required to keep yourself below the maximum force limits, not to mention that you'll be chasing minimum material to reduce weight. I think generally Kevlar has been ditched as an energy absorption material. I'm not certain but I think this is because of the general difficulty getting a good bond between the matrix and fibre.