Terminology and ?

General Composites Discussions Composites Talk
#1

What is the term used when joining two or more composite pieces?

Also Is there a thread I can’t find, that talks about the proper techniques.

Thanks

Greg

#2

bonding composite layers???

#3

bonding…
there are lap joints, butt joints, feathered joints, t joints, joint joints, etc.

#4

Are you referring to these terms ?

#5

I love this forum! LOL

This does answer my questions about jointing and the terminology.

Thinking of a example of carbon fiber chassis joining.

Is the idea to make all your pieces, Then join them together with one, or all of the joining methods? Then finally vac-bag/heat?

Thanks

Greg
.

#6

Greg,
The new Mclaren supercar is using some interesting molding techniques.
Most high end cars with carbon bits in them make lots of individual carbon parts and then bond them together using special adhesives that will rival the strength of welded joints. The new Mclaren uses a “monocoque” technique for the main passenger area and frame and it is extremely complex and difficult to do. They tout that they are the first company to make a monocoque frame with hollow sections in it and their manufacturing methods are not something you may be able to find easily if at all. Monocoque essentially means “one-piece”.
although molding individual carbon parts may often involve using a mold and vacuum pressure there are many other ways for joining those pieces together.
Vacuum bagging is nice when you need to apply a little bit of pressure over a large area and to do it very evenly. but not great when you want lots of localized pressure over a small area. A vacuum bag with a full vacuum is only good for the atmospheric pressure that day…about 14psi. allot of molding operations need allot more than that. That’s where large pressure chambers called Autoclaves come in. That’s essentially a vacuum bag inside a pressurized chamber. Some Autoclaves can add up to 100 additional psi to the molding operation and those will also add heat to the curing operation. Heat is needed to cure the special “prepreg” carbon which is usually kept frozen until it is molded. It is carbon that already has the epoxy resin “pre-impregnated” in it.

Hope this helps.

#7

It does thanks!

G

#8

@Mando: Basicly what Bugatti SRL did in late 1980s / beginning 1990’s, with the EB110. (monocoque made by Aerospatiale, as at that time automotive composites were still way behind)

#9

The aventador monocoque for example is made frim several individual carbon parts. They are produced by different methods, some are autoclave parts, sone RTM parts and others termoplastic parts. They are all glued together to the mono you see on your picture.
The McLaren MP4-12C mono is completely made by RTM with hollow plastik tanks and comes ready out of the tool including all inserts.
The Bugatti Veyron mono is complete made by autoclave parts and then glued together.
A monocoque is not a one piece build thing, normal it means a closed construction for the driver and was build by Lotus. Correct the new cars don’t have a monocoque, they have a carbon fibre chassis.
But everybody knows what is ment if you say cfc monocoque.