carbon fiber cylinders for drums - need advice 1

[jlyerly]

I want to make musical instrument drum shells from carbon fiber - basically cylinders. I am not an engineer, and do not have much experience with CF. I could (and will) go through the trial and error process, but I would appreciate any advice or help that could be offered.

Typical sizes would be 12-16" dia. and 5-16" lengths. Most of the stress would be along the length, of course. I have considered using CF layups only to acheive thickness and strength, but that seems to be prohibitively expensive. I have also considered using a CF skin over a foam core.

Any advice would be appreciated. I am just trying to gain as much knowledge as I can moving forward.

Thanks in advance.

 

[rnd2]

Consider why you have to make the drum shell from CF. CF really has only one outstanding property and that is stiffness. If it is for cosmetic reasons perhaps start with woven glass. If you are considering making for production contact a filament winder for basic GRP tubes and finish the visible layer with woven CF. GRP is reasonably stiff, tough, and a lot cheaper. Strength wise, 3/16" WT would be somewhwere to start.

 

[Compositepro]

You can also use wood or paper impregnated with epoxy as a core material.

 

[sreid]

Check out Aircraft Spruce for composite books and materials.

http://www.aircraft-spruce.com/

 

[jlyerly]

Thanbks for the replies. The reason for CF is rigidity, resonance, and weight. The idea is to have a thin shell that is still rigid. Yes, wood plies do that pretty well too.

I'm thinking that a high density foam core might work, like they are using here:

http://www.robotcombat.com/marketplace_carbonfiber.html

This would save on the amount of CF used. Not sure how thick the outer skins would want to be, though.

I will check out those books. Thanks.

 

[jhardy1]

I don't really know much about drums (least of all CF drums!), but I would query your assertion that: "Most of the stress would be along the length". The drum skin needs to be in tension, and therefore would pull radially in around the rim of the shell. If you don't have adequate radial stiffness in the shell, it may tend to buckle (oval) in the radial direction.

(I know that one way of tensioning a drum skin is to pull it over the rim of the shell and along the axis, but intuition suggests that radial buckling might be more critical than longitudinal buckling for a thin cylindrical shell in such an application.)