Bending graphlite rod

Fred,

The graphlite derives its strength from the fact that the individual
carbon fibers are all kept very straight. Even when slightly bent, the
fibers in any local vicinity are still relatively straight. If you try
to heat it past its transition temperature while bent, the fibers under
more tension will try to displace toward the fibers under less tension.
I believe that you could do this; transition temperature is transition
temperature; I don't think you got it hot enough... But then you would
lose the basic strength characteristic of the material.

Bob's suggestion of using/joining smaller diameter rods is a logical
one. The pre-stress here may be something that you can easily live
with...

When joining with other same diameter rods or larger diameter rods for
axial loads, you need to have enough length such that the surface area
of the adhesive around the rod times its psi strength equals the psi
strength of a rod. For a round rod in tension L has to be approx. 80 D;
assuming an adhesive strength of 1,000 psi. So you can see that smaller
diameter rods have to have less length joining.

I have been giving some thought as to how to use this material other
than in a strictly axial loading, e.g. wing spars. Still thinking...

Blue skies,

Tom





wrote:
Bob Kuykendall wrote:
J.Kahn wrote:
The stuff is rolled into coils for shipment. Scroll down and check out the
flat version bent by hand into a half circle.

I've seen a picture of graphlite (TM) rod bent into a loop with a
radius
of about an inch or so. Now, imagine that you want a 2" diameter
ring, like a key ring. Would you bend the rod into a circle and glue
the ends together?

I think not!


Yup, that's the way I get it, spools of 1000 to 1500 feet.

As you probably noticed, when you take it off the spool, it
straightens out. I want to shape it so that it is curved without
any applied stress.

--

FF