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#1 Nathan

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Posted 08 December 2011 - 18:37

Is it possible to glue, perhaps bolt, carbon sandwich panels to form a body/frame structure in the same way stamped metal is welded together?

Thanks!

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#2 Tony Matthews

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Posted 08 December 2011 - 18:58

Lotus managed it with their 'origami' chassis, Type 91 and 95 to name but two.

#3 Greg Locock

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Posted 08 December 2011 - 21:32

It is possible, it may even result in a reasonable structure, but it is nowhere near as good as moulding the piece as one part.

On solar cars we used to build the internal body structure from flat panels of carbon prepreg on nomex cores. To join them together we cut them, much like in woodworking, and joined them with glass tape and an epoxy or possibly polyester resin/microballoon mix. This was fast, light, stiff, but probably not especially strong. For the later ones we went to vac bagged prepreg over foam cores.

Luckily we've never had to find out how strong they are.




#4 mariner

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Posted 08 December 2011 - 21:48

You can ,I believe, connect most sandwich composite panels by gluing , the issue is whether you use overlap strips and rivets to join them with a good safety margin for erratic bonding etc. or rely on very tight tolerances to "butt glue" the panels. Also whilst using flat pre prepared panels avoids expensive moulds you still have to consider if heating and/or pressure is required to get a good joint bond.

IIRC Lotus brought out a carbon / kevlar tub the same time as McLaren did the fully autoclaved one at Hercules. The Lotus technique was cruder than the McL one in that the whole composite was laid up on a flat bed and then folded up around pre fabricated bulkheads before it was fully cured. This led to a "multi flat panel " look to the tub but the whole tub had a continuous outer skin as I understand it.

As ever, if you go to Peter Wright's book " Formula 1 technolgy " it is all laid out (!) on page 316 - complete with a drawing by a certain Mr Tony Matthews!!

#5 Tony Matthews

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Posted 08 December 2011 - 22:46

Without looking at the book, even though it is only a couple of feet away, you are right, mariner. It was essentially one complete panel, made, I believe, on a massive, expensive, glass platten. This was then marked out and a strip of the top (inner) skin routed out and the panels folded up, the core allowed to crush. That way the outer skin remained inact, and carbon tape was used to reinforce the glued joints inside, However, I think the bulkheads were pushed into place after the foldin' and a-gluin', and bolted in place using bobbins bonded into the tub, with very small - 4BA? - bolts... Fascinating.

#6 Lee Nicolle

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Posted 08 December 2011 - 23:10

A little off subject but how long does carbon fibre retain its strength.
I have seen broken bits from F1 cars that seems to have deteriorated severely in a few years hanging up on workshop walls. To be fair these were endplates, floors and a front wing that seems to have faired better. One would hope the tubs are far better otherwise these cars are undriveable now.
And not quite in the enthusiast, vintage racecar restorers means of restoring these tubs.

#7 J. Edlund

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Posted 09 December 2011 - 16:43

A little off subject but how long does carbon fibre retain its strength.
I have seen broken bits from F1 cars that seems to have deteriorated severely in a few years hanging up on workshop walls. To be fair these were endplates, floors and a front wing that seems to have faired better. One would hope the tubs are far better otherwise these cars are undriveable now.
And not quite in the enthusiast, vintage racecar restorers means of restoring these tubs.


Degradation is mostly a problem with the epoxy matrix as I understand it. UV light seems to be the biggest issue, but water vapor is also a problem. Use of some protective coating seems to be a good idea to protect these parts.

#8 Lee Nicolle

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Posted 09 December 2011 - 23:11

Degradation is mostly a problem with the epoxy matrix as I understand it. UV light seems to be the biggest issue, but water vapor is also a problem. Use of some protective coating seems to be a good idea to protect these parts.

I thought that was the case. The wing which was painted seems ok, the floor fell off the wall!! as the bracket pulled through the material.
Though I dont think I want to crash an old carbon tub. It will probably explode!
Fibreglass loses strength over a few years,and does not like UV. Kevlar seems better.

#9 Greg Locock

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Posted 10 December 2011 - 01:33


I think it is the resin that is failing, not the fibre. I have a 25 year old glass fibre helmet that looks brand new, I only wore it for a couple of years and gave up riding.

#10 ray b

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Posted 10 December 2011 - 02:53

polyurethane breaks down in sunlight uv
as do epoxy
both turn from clear to yellow then over time crack and craze in to dust
if unpainted esp here in the sub-tropics

the glass fibers will survive fire [boat burning ]
and look just fine afterwards

but I am unsure about carbon as it may oxidize over time

#11 cheapracer

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Posted 10 December 2011 - 07:48

These guys aren't very far from me, wish I had half a clue on the subject ....

http://www.chemshine...bon/Product.htm

#12 Lee Nicolle

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Posted 11 December 2011 - 23:31

I think it is the resin that is failing, not the fibre. I have a 25 year old glass fibre helmet that looks brand new, I only wore it for a couple of years and gave up riding.

But probably not in direct sunlight. A 25 y/o helmet if stored inside should not deteriate much at all, and ofcourse it is painted. But that is part of the reason why that helemets only have a limited life for motorsport. But 90% of the discarded ones are still fine.

#13 Greg Locock

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Posted 12 December 2011 - 03:10

Sorry, yes I should have said, it has a black gel coat and has been in a box for 23 years.

#14 Bloggsworth

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Posted 14 December 2011 - 21:39

polyurethane breaks down in sunlight uv
as do epoxy
both turn from clear to yellow then over time crack and craze in to dust
if unpainted esp here in the sub-tropics

the glass fibers will survive fire [boat burning ]
and look just fine afterwards

but I am unsure about carbon as it may oxidize over time



Most plastics break down under the effects of UV, its just a question of how long. We used to mould housings for high level Brake-lights for Australian Transit vans, we had to paint them with a hideously expensive UV resistant paint or they would have crumbled in short order.