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Author: Subject: Carbon fibre and GRP chassis
Gakes

posted on 7/4/08 at 08:13 PM Reply With Quote
Carbon fibre and GRP chassis

Hi guys and gals

I have been doing tons and tons of research on the ultimate middy road-going sports car for a while now and only recently have I thought of using carbon and glass fibre in my chassis. Maybe a front tubulalar section for suspension that bolts onto a carbon/glass fibre mid/passenger section (kind of like a reinforced bucket) that bolts onto a rear section that houses the engine and rear suspension.

Has anyone here ever attempted one of these possibilities or am I a bit off track again?

I want to make my car as modern as I can, and try to incorporate different materials. If theres anyone looking to go this route, I'd love to chat and exchange info.





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Paul TigerB6

posted on 7/4/08 at 08:21 PM Reply With Quote
Very advanced for many on here but there are a few others doing similar to what you plan.

You might like to have a good read here for inspiration.

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Volvorsport

posted on 7/4/08 at 08:31 PM Reply With Quote
certainly possible .

i was going to do that until i got side tracked .





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Gakes

posted on 7/4/08 at 08:33 PM Reply With Quote
Cheers Paul. I have come across the DP1 already. very well refined design he has there. Still uses a tubular frame throughout though with a carbone fibre shell. What I am looking for is info on how strong the carbon/glass fibre chassis are and if anyone has tried it, is it costly? Recently, carbon fibres' popularity and newly found manufacturing processes has brought down the price a bit, so its kinda in reach. This is from a South African context





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Gakes

posted on 7/4/08 at 08:37 PM Reply With Quote
Volvo sport

Have worked out anything in the process? ...design, costs, strengths???





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nitram38

posted on 7/4/08 at 08:41 PM Reply With Quote
I hate to burst your bubble, but carbon fibre is a bit more complicated to make good strong bulkheads and the like.
The technology that goes into them to make them strong means using other fibres, weave patterns and an autoclave big enough to remove all of the air.
Unless you have a bottomless wallet or your dad owns Maclaren, I think you should give it a miss. (at least for structural componants)



[Edited on 7/4/2008 by nitram38]






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Richard Quinn

posted on 7/4/08 at 08:43 PM Reply With Quote
Unless you have significant experience of this type of construction I would advise against it. I tinker with carbon fibre/epoxy moulding and have done for many years. Carbon fibre can provide impressive stiffness for a given weight but the impact resistance is less than impressive.
Most exotic composite race cars are built using aluminium (or similar) honeycomb materials faced with carbon fibre and any moulded parts are generally made from pre-preg which helps achieve the optimum resin content with a panel containing 4 or 5 layers of carbon fibre measuring less than 1mm in thickness. This type of moulding requires the use of an autoclave to cure under elevated temperature and pressure. It is possible to cure in an just in a programmable oven but my one attempt at moulding pre-preg ended up with me achieving my strongest bond ever. Unfortunately it was the bond between the part and the mould (even using proper chemical release agents)! Oh yes, and pre-preg usually needs to be stored frozen.

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Gakes

posted on 7/4/08 at 08:50 PM Reply With Quote
Nitram38,

thanks for the comment. I have worked and designed for a fibreglass mould and plug manufacturing company. Guys that worked in the factory told me that carbon fibre is worked in the same way that GRP is. I know that Huge car companies use ovens to cure them and machines to extract air from them. But, the same basics apply to GRP and carbon fibre.... Apply resin, then the mat, roll out air bubbles then repeats these steps for another layer. I have come across a site of a kayak manufacturer. He uses carbon fibre in that same way





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Gakes

posted on 7/4/08 at 08:54 PM Reply With Quote
quote:

Richard Quinn

Unless you have significant experience of this type of construction I would advise against it. I tinker with carbon fibre/epoxy moulding and have done for many years. Carbon fibre can provide impressive stiffness for a given weight but the impact resistance is less than impressive.
Most exotic composite race cars are built using aluminium (or similar) honeycomb materials faced with carbon fibre and any moulded parts are generally made from pre-preg which helps achieve the optimum resin content with a panel containing 4 or 5 layers of carbon fibre measuring less than 1mm in thickness. This type of moulding requires the use of an autoclave to cure under elevated temperature and pressure. It is possible to cure in an just in a programmable oven but my one attempt at moulding pre-preg ended up with me achieving my strongest bond ever. Unfortunately it was the bond between the part and the mould (even using proper chemical release agents)! Oh yes, and pre-preg usually needs to be stored frozen.




OOOOh. so it looks like im pissing in the wind again.

How about glass fibre chassis anyone?





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Triton

posted on 7/4/08 at 09:03 PM Reply With Quote
oooo glass fibre chassis....you been peeping





My Daughter has taken over production of the damn fine Triton race seats and her contact email is emmatrs@live.co.uk.

www.tritonraceseats.com

www.hairyhedgehog.com

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Griffo

posted on 7/4/08 at 09:04 PM Reply With Quote
fo9r the cost associated with it you may be better looking at aircraft grade ali? then again maybe not. im sure someone will know more than me
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Richard Quinn

posted on 7/4/08 at 09:05 PM Reply With Quote
I'm not wanting to p*ss on anyone's chips but even something like a fairly standard West epoxy laminate really needs to be vacuum bagged to get a decent strength to weight. It also needs to be cured and post-cured at a higher temperature than a polyester resin to achieve full strength.
It isn't a black art (well, I suppose it is black and does look nice!) but if you are looking at a basic wet lay up then I certainly wouldn't do it for anything structural/safety critical

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Triton

posted on 7/4/08 at 09:09 PM Reply With Quote
I'm using fibreglass to make mine but using something groovy in the ingredients to add stiffness yet weighs nowt...





My Daughter has taken over production of the damn fine Triton race seats and her contact email is emmatrs@live.co.uk.

www.tritonraceseats.com

www.hairyhedgehog.com

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Gakes

posted on 7/4/08 at 09:18 PM Reply With Quote
quote:

Triton

I'm using fibreglass to make mine but using something groovy in the ingredients to add stiffness yet weighs nowt...



C'mon....let me in on that secret pls.





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Triton

posted on 7/4/08 at 09:27 PM Reply With Quote
Loads of blue smarties, hardest bit is eating all the other ones first..and doesn't matter then if car isn't any good as will be too fat to get in it anyway..


Seriously it's not that new but it is for a car so if i write it here do you promise not to let anyone else read it?....





My Daughter has taken over production of the damn fine Triton race seats and her contact email is emmatrs@live.co.uk.

www.tritonraceseats.com

www.hairyhedgehog.com

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Triton

posted on 7/4/08 at 09:33 PM Reply With Quote
Gakes,

u2u'd you meduck

Mark





My Daughter has taken over production of the damn fine Triton race seats and her contact email is emmatrs@live.co.uk.

www.tritonraceseats.com

www.hairyhedgehog.com

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RK

posted on 7/4/08 at 09:41 PM Reply With Quote
Doesn't anyone build a car for 250 anymore?
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Volvorsport

posted on 7/4/08 at 09:43 PM Reply With Quote
www.darrian.co.uk





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Gakes

posted on 7/4/08 at 10:03 PM Reply With Quote
thanks guys.

Triton, I U2U'd u 2 mate. This must be one of the greatest forums if not the best ever. So much knowledge floating around.

Has anyone made any progress on the 3D model hosting or something? I have a few models I dont mind sharing





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worX

posted on 7/4/08 at 10:05 PM Reply With Quote
Is it a layer of sandwiched foam?
quote:
Originally posted by Triton
Loads of blue smarties, hardest bit is eating all the other ones first..and doesn't matter then if car isn't any good as will be too fat to get in it anyway..


Seriously it's not that new but it is for a car so if i write it here do you promise not to let anyone else read it?....







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Volvorsport

posted on 7/4/08 at 10:13 PM Reply With Quote
the other thing you can use is parabeam .

its used in grp pressure vessels , and can be used with normal resin .

or a couple of sheets of teklam to get you going .

do a google .





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Triton

posted on 7/4/08 at 10:28 PM Reply With Quote
The new smartie tubes are just right as nice shape and glue together easily. Like i said before the down side is the amount of munching to get said tubes is a pain but needs to be done.
Place the odd blue one for right affect and bingo....only smarties have the answer!

But that might be all a load of gobbledygook for all I know...it may well be the yellow ones needed...





My Daughter has taken over production of the damn fine Triton race seats and her contact email is emmatrs@live.co.uk.

www.tritonraceseats.com

www.hairyhedgehog.com

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twybrow

posted on 7/4/08 at 10:46 PM Reply With Quote
From the sound of it, what you would like to build is the same basic design as the Mclaren SLR (our sister company builds them and the Koenigsegg - damn they look fine in bare carbon!). The design that goes into the tub is vast. When you think of using composites, then you need to consider so much more than just the material choice. CFRP is a wonderful material, assuming it is processed well, and used correctly in a well engineered design. The geometry, the material, the thickness, the process etc etc etc can all play a massive role in determining the final strength/stiffness properties.

It is by no means impossible for an amateur builder to design and manufacture something really effective (I think Syd Bridge has done something similar in the past?). But personally, I wouldn't. As you cant design, test and redesign, you would need/want to over engineer it to be on the safe side, then you may find other materials would have been better to work with.






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jono_misfit

posted on 7/4/08 at 11:08 PM Reply With Quote
There are a number of hillclimb cars made of pre preg carbon fibre that were designed and manufactured at home. A lot are done using vaccume bagging and elevated cure, not under pressure in an autoclave.

There are a lot of them that have survived being attacked by moving tree's / crash barriers without significant injuries to the drivers.

Personally i think one of the biggest problems will be getting decent quality carbon, at a sensible price, in a sensible time frame. Its too popular.

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Benonymous

posted on 8/4/08 at 05:06 AM Reply With Quote
Years ago I read an article in a motoring magazine about how Morris 1100's were made in GRP for sale in Spain (I think). I've Googled it but there doesn't seem to be any references to it anywhere. It wasn't an April fools joke, the article was supported by a number of pictures showing the mould making process. As I recall, the whole car was made of regular fibreglass and polyester resin. There were a few kits in the 70's with fibreglass tubs too I think. There's no reason why a fibreglass tub wouldn't work. Special attention would have to be paid to areas of high stress but it'd be perfectly feasible. The main difficulty you'll have with it is getting it past the regulations. A tubular space frame has much more easily calculated strength. As otheres have pointed out, the way a structure is made with composites and the techniques used will have just as big an effect on the final strength of the finished part as the design itself.

Don't forget, you're the crash test dummy in the equation.

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