Composites Basics by A.C. Marshal says that hand laid wet carbon and

glass

have identical tension and compression.

Kevlar is about 60% stronger in compression and 12.5% in tension.

page 10-10
Eric Ruttan

Eric Ruttan,

Good point Eric- why this is so is because carbon needs a very uniform resin
saturation to achieve it's Maximum strength.
If one area is slightly lean it will then be the weakest point and will fail
at that point.
Hand lay-up techniques are NOT uniform, no matter how hard you try,
therefore you always have weak points. The weak points would be no stronger
than e-glass - they could also be weaker or more prone to failure because of
the catastrophic failure characteristics of Carbon.

You could get an expert to lay-up Carbon (by hand) and you will get a
different result every lay-up - so I have trouble agreeing that Carbon is
the same as e-glass, however E-glass and S-glass is much more forgiving.

When used in a non-structural area (cowl) this is not a problem.
When used in conjunction with e-glass (as a stiffener) this isn't a problem
either i.e. flaps, rudder, elevators etc.
George (down under)

 
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