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Magnum164
07-22-2011, 10:24 PM
I have been looking for about 8mm square Carbon Fiber bar. Any one know of a source that can provide about 12" lengths. I have found several sites that sell CF, but nothing near that thick.

Needs to be gloss one side at least.

Evan
07-22-2011, 10:35 PM
Try Marshall. They might be having a yard sale soon.

Magnum164
07-22-2011, 10:46 PM
Marshall Space Flight Center, Marshall Fabric Designers, Marshall County?

Links would be helpful...

Evan
07-22-2011, 10:48 PM
The space flight center. I was semi joking.

Try a kite shop. Some have all sorts of carbon fiber/epoxy sections.

AiR_GuNNeR
07-23-2011, 09:09 AM
Aerospace Composites, or Composites Structure Technology might carry them.
The gloss side may be a problem, but a thin coat of finish cure epoxy would shine it right up if needed.

http://www.acpsales.com/
http://www.cstsales.com/

Black_Moons
07-23-2011, 10:56 AM
Considered just making your own? how strong does it have to be? is it mainly for looks?

I would probley take a 7mm~ square chunk of wood and wrap carbon fiber around it and epoxy it. Leave the wood inside (Use balsa wood or cardboard if your worryed about weight? iv beaten someone over the head with a huge (1'x1'x2') block of balsa before... It dented the balsa and messed up his hair slightly. :P

chrisfournier
07-23-2011, 11:17 AM
They sell CF bars used for guitar truss rods. You'd likely have to glue up two and do a bit of work to get your specs.

Magnum164
07-23-2011, 03:54 PM
Considered just making your own? how strong does it have to be? is it mainly for looks?

I would probley take a 7mm~ square chunk of wood and wrap carbon fiber around it and epoxy it. Leave the wood inside (Use balsa wood or cardboard if your worryed about weight? iv beaten someone over the head with a huge (1'x1'x2') block of balsa before... It dented the balsa and messed up his hair slightly. :P

I really did not want to make a composite assembly myself but that may be the cheapest route. DragonPlate makes Honeycomb CF sheets in 7mm that might work. Will just have to run it through some FEA analysis and see how it works. I am thinking a composite may be too strong for what I need. The design is to really build on CF's ability to be more flexible than aluminum and returning to it's original shape. AL will simply bend. CF will eventually snap, but takes a lot more force than my application. A CF composite with solid core probably will not flex like I need it to.

Evan
07-23-2011, 04:19 PM
I have used CF materials in some applications. It does have extremely high stiffness for its weight. Bending should be very limited as it produces eventual fatigue damage long before the ultimate yield point is reached. From my personal experience what seems to happen is development of microscopic delamination zones all through the material. This doesn't affect most of the bulk properties measurably until it becomes severe. What it does do is to lower the ultimate yield strength gradually. The amount of fatigue appears to be ~exponentially correlated to the amount of strain applied below the ultimate yield value. The material is very non-linear near the ultimate yield.

The behavior is similar to the fatigue performance of 7075-T6 aluminum where the ultimate yield point becomes lower than the original plastic yield value so it snaps before the plastic yield point is reached. That type of failure mode is consistent with the failures observed in the composite rudder failures on the Airbus 300 series aircraft.