Carbon panel supported by SS beam

[flyerfly]

Hello,

I need to support a long carbon panel (19 feet) with a stainless beam and they need to be bonded together to prevent leaking etc. Only problem is the CTE would cause a difference of around .25 inches over that length and the temps. it will opperate at.

Does anyone know of a good elastomer potting system that I could used to stick these two together? The interface only needs to carry a minimum of tension and will be almost entirely compression and shear.

I thought of putting a health layer of glass between them to reduce the CTE jump but would like others thougts on this too.

Thanks for any input.

 

[berkshire]

flyerfly
If the panel is lightly loaded you might look at rtv silicone rubber
B.E.

 

[Compositepro]

Gradation of the CTE with a glass layer was mentioned in an earlier post but that will not help at all. What you are trying to accomplish is to put a thick, highly elastic, layer between the adherends to accomodate the strain differences. Glass is not highly elastic and will not help in any way.

I'm not sure that what you are trying to do is possible. What loads do you actually need to transfer from the panel to the beam? Some sort of slip joint may be more practical.

It all depends on how much stress and strain are involved. 0.25 inches over 19 feet is not all that much, but how stiff are the panel and beam? Warping is also going to occur.

 

[MechanicalChef]

0.1% (linear) strain isn't very much at all. :hmm:

 

[flyerfly]

The loads are moderate (.7 psi) and will result in around 15,000 lb on the panel. I still might make the beam out of carbon but the cost is significantly more then steel...and the stiffness is not there for the grade of carbon that we are using.

At this point I am still brain storming...I will have to work out the lamination schedule to see what kind of strain it can handle and then do a test to verify.

It is not possible to have a slip joint because of leaking (among other design issues).

Compositepro - the panel is pretty stiff, it has about .2 of carbon laminate on each side of a 2 inch core. Stress is not the limiting factor on this design as much as deflection. I have thought of warping at temperature extreems but I don't think it will be much due to other geometry present...although it will put stress on that geometry for sure.

Does anyone know of a company that makes carbon pultrusions that are large? By large I mean 4"x4" with maybe half inch wall or so. This would be primarily uni with some winding fillaments too.