Bending graphlite rod

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.

I don't think it's necessary to eliminate all preload. In the general
scheme of things, I would think that the amount of stress built up in
hand bending a graphlite rod to an airfoil profile is insignificant. In
wood rib construction it's only necessary to steam the forward part of
the top cap where the bend is extreme due to limits in the flexibility
of the wood, but in most of the rib the wood is under bending preload.
I would extend a graphlite top rib cap as far forward as it can be
comfortably bent by hand and use a wood nose block for the very front
for the nose radius.

The bigger problem is designing an effective way to join the pieces so
the joints are as strong as the graphlite pieces if it's going to be a
truss rib, using fibreglass, or maybe using pieces of carbon fibre sheet
cut into gussets and gluing it together like a wood rib.

John