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Old Mar 10, 2013, 08:46 AM
Registered User
Joined Mar 2013
1 Posts
Question
Basic bladder moulding techniques

HI guys,

I'm actually trying to make a carbon fibre tube with an oval profile and a 45 degree bend. I have never used carbon fibre before and I have been reading as much as I can on the web. This forum is by far the best source of info. that I have found so far. There seems to be a huge amount of experience here and I was hoping that someone could give me some basic pointers to get started.
I intend to make a fibreglass mould - I would like to have one CNC'd from aluminium but can't really afford that at the moment. I also intend to make a bladder with the technique described by one of the guys on here. Adam I think. with stretch plastic membrane.
The layup is puzzling me a little though, I presume that for a tube part, a carbon fibre sock/sheath would be the best option both for structural strength and also for the finish. Would people agree?
The part has to be very strong taking 220lbs maybe even more as well as considerable shock load - could anyone give me any iideas what kind of thickness of material might be required. I will do a lot of testing but as the materials are quite expensive where I live I'm hoping to find out as much as I can to begin with.
Also anyone know any good resources to start learning about composite fabrication?
Thanks a lot in advance.
Tony.
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Old Mar 11, 2013, 11:58 AM
Master of the Wind
G Norsworthy's Avatar
United States, CA, San Jose
Joined Sep 2008
1,125 Posts
Here is a handbook

http://www.r-g.de/en/

Also some good articles here.

http://www.charlesriverrc.org/articles_modeldesign.htm
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Old Mar 11, 2013, 02:34 PM
Composites guy
North OC, Ca.
Joined Jun 2005
1,155 Posts
Shock load and carbon generally do not mix well.

Glass composites are strong and more durable.

Bends in fiber reinforced parts should have larger radius bends to avoid stress concentration.
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Old Mar 12, 2013, 03:53 AM
Entropy Happens!
Jim.Thompson's Avatar
Bellingen NSW Australia
Joined Aug 2008
6,054 Posts
Quote:
Originally Posted by tonytc View Post
HI guys,

.............................The part has to be very strong taking 220lbs maybe even more as well as considerable shock load -................Tony.
Not enough information here Tony. How is the "220 lbs" load applied? In what vector etc? Or is it in compression?
If you were to describe the application, others could respond more meaningfully.
Your bare statement above is just about meaningless to the reader.

I'm with Sarmoby here. Also, carbon is not a good material to start to learn composites with. It's harder to use than glass, much more expensive and less forgiving of less than optimum layup technique etc.

As for composite information, just keep reading these forums. Lots of good information and generous help available. Good luck.

Jim.
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