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Risk,
You made a few mistakes.
Yes steel is strong, CF even stronger. But wood is NOT stiffer
than steel. The only material stiffer than steel is CF and Wolfram
(tungsten) and some other exotics.
Impact resistance has nothing to do with stiffness (youngs
modulus)
but more with the tensile strenght and ability to absorb
energy (or the Sharpy /Izod value). Steel wins.....
Nice of wood and CF that it shows no fatige , it is
strong enough or it breaks!
I think another risk of GRP or composite material is that you
have a porosity and pressure built up inside the material.......
Regards, Emile van Essen
former material testing engineer
Hugo,
While steel is very strong, it is not at all stiff relative to it's
weight. Wood is actually 7 times stiffer than fiberglass, and 5x stiffer than
kevlar, with very high cycling rates. By applying kevlar to the outer surface
any impacts would be spread out over a larger surface. If carbon fiber were
used on the inner surface of a wooden hull, it would serve to strengthen the
structure even more because the carbon is stiffer than wood. In the end, I
think it depends on the thickness of the structure and of course the
composites used. I'll have to run some destructive tests to see if any of this
is really feasible.
Risk
In a message dated 1/19/2005 7:56:45 A.M. Eastern Standard Time,
hmarrero@hboi.edu writes:
Hello all,
Just more food for thought for those brave souls
who want to build their own pressure hull with fiberglass and
wood.
Have you considered in your design the effects of
submerged impact, or impact on the surface with another vessel (while you
are inside)?
just wondering,
Hugo
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