D-Shaped Tube

General Composites Discussions Composites Talk
#1

I’m working on the design aspects of creating a hollow fiberglass “D-shaped” tube. Internal dimensions would be maybe 30mm Height x 40mm Wide at base. This piece would then be secondarily bonded to another structure (along the flat side of the “D”) and then secured with additional layers of fabric vacuum bagged into position.

(I want a better bond than is available using a round tube with fillets)

For the male mold, I’m considering some kind of foam that can be dissolved via solvent after curing.

Will that work, and if so what kind of foam do you recommend?

#2

Should have mentioned these poles (actually several to be made) will be between 2 & 5 meters long

#3

So these essentially act as a stiffener hat? Why not make it more of “U” shape with flanges for bonding? Tooling will be much simpler.

#4

They will be used to secure netting that will be walked/bounced on. The tube gets secured to the structure then some slots are cut into it at set intervals. Afterwards, a solid aluminum (or carbon?) rod is inserted into the tube to serve as a lashing point for the netting. I’ve linked a web page of what I’m referring to. (See 3rd or 4th picture down)

The reason I’m wanting a D-Shaped tube (rather than a U-Shaped)is simply for more surface contact since this part can occasionally see some high loads.

#5

Weblink didn’t work.
Try

http://cartersboat.wordpress.com/page/2/

#6

Is that your farrier?

#7

No, someone else’s. I’ve yet to start - still gathering equipment, parts and supplies. But hey, I did get a VacMobile here recently. :slight_smile: Super nice equipment there! I’m hoping to start some small things by this fall. But until then I just keep hammering away at research, building the thing over and over in my mind and scouring these boards.

I did run across some good epoxy that you guys might want to take a look at. It’s the 2110/9218 series from Epoxi.com (290cps - 86D Hardness - 210F HDT - 499,000 PSI Tensile Modulus - 12,600 PSI Tensile Strength - 5.8% Tensile Elongation - 494,000 PSI Flexural Modulus).

Those are the best numbers I’ve run across yet for a room temp Stage-B cure. It does require a Post Cure to get the full properties.
The only downside is the 85 minute gel time at 77F.
At this point I’m thinking a whole lot of plumbing can remedy that for the larger infusions. But this is me speaking… nothing but book knowledge at this point.

I think I’ve reached the point of knowing just exactly how much I DON’T know… Kinda depressing.

:slight_smile: