Talk Composites - The Forum for Advanced Composites

carbon and grp hybrid laminate

http://www.talkcomposites.com/Topic4231.aspx

By benet - 1/12/2013 2:02:05 PM

Hi all

In the interest of increased rigidity in a panel........


Ive been producing skateboards using a 10mm wooden core with 600 weight plain weave glass fiber skins top and bottom. They work pretty well.

However i have seen boards using a carbon skin on the underside which is done with the intention of increasing stiffness.

I was wondering about this and thought that, given in my case the core is skinned top and bottom and that grp is generally stronger in elongation than compression i would be better of if i skinned the upper side of the board in 450 carbon and the underside still with 600 grp.

My thinking is that i would have a better balance in the strength of the skins ( the upper being stronger to withstand compression the lower being slightly weaker but effectively strong in elongation) and hence a stiffer board than if i just skinned the bottom in carbon and left the top in grp...?

Im wondering if the use of carbon on the underside of a skateboard is more about aesthetics  (as its on show, the top normally covered in grip tape) and less about engineering.

Any experienced advice much appreciated.
By benet - 1/13/2013 9:07:27 PM

@ Matthieu 
yes, i do that on some boards mostly for aesthetics and flex ( the boards look nice with a wood outer ) . But i tend to think when rigidity is paramount not flex, which it is in some types of board, the further apart the fg or cf the stiffer the result.

Id be happy to hear any evidence against that. Of course a stiffer core will always help to some degree but weight comes into play and generally the wood is lighter. some boards are made with cores of foam or balsa wood that have no real strength at all other than the ability to keep the laminates apart. however thicker and hence heavier laminates are required to make up the strength.

Also as a bonus, another thing i think is going on when you skin the outer of a composite board is that the skin actually holds the wood core together stopping it from being able to split so readily and hence extends the point of failure.