spectra vs kevlar?

[sigurd]

I have a question.
Consider a cored slender hull. You have one layer fabric each side. Obviously one of them should be 0'/90'. Does it make sense to skew the other to +-45' or is it better to keep the two layers in the same direction?

Originally Posted by sigurd

Does it make sense to skew the other to +-45' or is it better to keep the two layers in the same direction?

The answer is yes...............
I used Glassmat for core simulation, but the result is the same with foam core (not the figures naturally).

[sigurd]

Thanks, good idea. Doesn't seem unlikely to me. But i haven't seen any examples of laminates using different bias each side of the core. Have you?

No, Sigurd.
But that does not mean that much, you know I´m building in wood / EP only. So, what have I seen?

[sigurd]

Coal soot? Rot? I asked because I am getting a 180gsm 2/2 twill with 50/50 carbon/dyneema, which will likely be enough each side of the corecell (which is on its way!) for structure. If I only could remember what it was that I was going to build... Must have been something highly fashionable.

Originally Posted by sigurd

Coal soot? Rot? I asked because I am getting a 180gsm 2/2 twill with 50/50 carbon/dyneema, which will likely be enough each side of the corecell (which is on its way!) for structure. If I only could remember what it was that I was going to build... Must have been something highly fashionable.

You should read: HOW MUCH ABOUT THIS SUBJECT HAVE I SEEN!!! NOT TOO MUCH, AT LEAST NOT ENOUGH THAT IT WOULD COUNT!!!
was that clear?
Coal, soot, and rot, yes on my steamers I had enough of all.
On my production boats rot is no issue, we saturate the veneer almost completely. Coal and soot yes, fumes too, sometimes customers emit such stuff if we present the bill.
180gsm 2/2 Twill??? what means 2/2 in this case?
Cannot comment your last sentence, I still do not know what you are going to build!!!???

Regards
Richard

[sigurd]

I understand. 2/2 twill means 2 over, one under, 2 over, etc in the weave - in both directions.. 0' and 90'.
From what I read, such weave is looser, but more easily conformed to curves, than plain weave (over, under, over...) The fibers also gets less kinks than PW - making it more fatigue resistant and giving it more compression strength.
http://www.sollercomposites.com/fabricchoice.html

Originally Posted by sigurd

I understand. 2/2 twill means 2 over, one under, 2 over, etc in the weave - in both directions.. 0' and 90'.
From what I read, such weave is looser, but more easily conformed to curves, than plain weave (over, under, over...) The fibers also gets less kinks than PW - making it more fatigue resistant and giving it more compression strength.
http://www.sollercomposites.com/fabricchoice.html

Thanks I got it, come back to subject later at night.
Regards
Richard

[sigurd]

If you are interested in further opinions on the subject of asymmetric laminates, see this SA thread.

[lymanwhite]

Interesting information. We used kevlar as an abraison layer just inboard from the outer skin, on the main hull of a carbon over end grain balsa tri.