Hi Ian

I only put those links up for information. I'm all for pushing the boundaries of whats possible to be home made in carbon but I also know that I'm no composites expert and I wasn't promoting the idea of a home made carbon roll cage at all.

I've put a couple of cars on their roof and really wouldn't want only a bit of composite between me and the griding road surface. I've got a nice steel T45 full cage on my car. It is surprisingly light for the size of structure it is. 

I'd set you're mind on some weight saving, cool looking, bodywork if I were you.  

Craig

"Apparantly they use some sort of anti-splinter process to ensure the cage does not shatter into shards if it is subject to an impact" They have worked with Airbus, i think they used  different type of carbon fiber or resin, its possible. Normally it causes shatter into shard if it is subject to an impact. You shouldn't try that because of safety.

I wonder if this is z-pinning?

You can prevent the "shattering  /shards" problem by simply using outer layers of Kevlar/CF mix ...   Also using a semi-flexible resin in the outer layers will help keep the structure less prone to fracturing into dangerous parts. (in effect constructing a much more flexible "bag" that can contain the CF "splinters" in case of a catastrophic structural failure)

Metal tubes (Aluminium Alloys or steel) that are kept at a level of hardness/toughness where you ensure that they are ductile, under the loads from a rollover or medium impact chrash, will mean thet they have to be heavy compared to similar strenght tubing that will take the impacts, but may crack at joints and also present dangerous edges.

So in metal roll-cages it is also a balance  ... done properly CF/Kevlar/Twaron should make exellent light weight safety cages.   (No F1 car has anything but composite "safety tubs")

To make it really efficient, one has to think outside the "tubular box" in my opinion, and construct a "cage"/ "tub" that takes advantage of the properties of a purpose built composite construction.

(Stiffness in the right directions - impact absorbance in the correct directions - anchor points reinforced with regards to the forces acting on them in both a chrash and a roll .. It can be done .. even hand built, and I would think that even severely overengineered for safety, it will still be as light as a steel cage, and can probably be incorporated into the inside cabin structure in a much less intrusive way ..

But you will really have to know how to engineer it ...

"Sapere Aude"... Dare to KNOW!

The written word is the only truly efficient vehicle for transmitting a complex concept from mind to mind...

103% of all people do not understand statistics...

Do not adjust our mind, theres a fault in reality :-)

Although I have dropped the idea now, I was thinking "outside the tubular box". Perhaps trying to integrate another structure into the existing bodywork so that the extra strength is hidden away. Maybe bonding a new composite structure to the existing GRP. It must be possible, but I now understand that it is a complex and skilled job and not for a beginner like me.

Just another car to look at is the Mclaren P1 GTR which doesn't have a cage as it's carbon monocoque already meats FIA roll over regs

Lotus Exige has a composite 'crash box' too. Can definitely be done, but it's certainly not something I would be doing before completing an engineering degree. 

The exige crash box is just on the front so doesn't cover roll over events.

No no I know. I was just talking about the use of composites in impact/collision and safety structures. 

Ah right, have you seen them?  Quite an interesting part in how its made.