[Date Prev][Date Next]
[Chronological]
[Thread]
[Top]
RE: [PSUBS-MAILIST] Carbon Fiber
Suds,
I certainly wouldn't suggest that you couldn't build a pressure hull out of
fibreglass or carbon fibre. I'm suggesting that there is always a risk
associated with any material that it will not perform to the listed
strength. Unfortunately, it seems that this risk is higher with many
composites than it is with metals, and also unfortunately, with current
testing methods (at least those that I know of) it is very difficult to
calculate the risk. I beleive that those are the reasons that you can't get
a carbon fibre hull certified by a classification society. Do you know if
there is any risk of significant crack propagation in carbon fibre in post
manufacture use? Are you using a glass, carbon fibre sandwich in your hull?
I suppose an advantage of a carbon fibre hull with regards to cracking, is
that if you have many layers, the crack will probably not spread between the
layers whereas with steel a crack will spread right through the hull.
Anthony,
I'm not sure if I understood you correctly but just in case (I learned this
the hard way)... If you are using a foam core as a mold, make really sure
you get the right kind of foam. The epoxy I used in my sub undergoes an
exothermic reaction while it hardens and releases a fair amount of heat,
which as you might have guessed can melt the inexperienced manufacturers
foam core, thus producing a long string of vulgar profanity and a lot of
extra work. As for classification, my thoughts would be that the only
reason to worry about not being able to classify your submarine (aside from
the sale issue you mentioned) is that generally there is a reason that they
won't classify certain designs. I speculated above as to why I think that
they won't. I think that as long as you realize what their reasoning is and
design accordingly it's not a problem. One other thing to consider is that
class societies are pretty slow to change their standards, but if you can
build something and prove to them that it does work, they will often
consider it on a case by case basis. At least that's the way they do things
with ships.
Wade
-----Original Message-----
From: owner-personal_submersibles@psubs.org
[mailto:owner-personal_submersibles@psubs.org]On Behalf Of Paul Suds
Sent: Sunday, August 13, 2000 8:39 PM
To: personal_submersibles@psubs.org
Subject: Re: [PSUBS-MAILIST] Carbon Fiber
Fiberglass and Carbon fiber can both be used as material for a structural
hull. I don't know where you got the idea that they are not strong enough.
It all depends on the design. I have my pressure bearing hull designed with
glass and carbon fiber using epoxy resin. One major advantage is that I can
make it any shape that I want. The outer hull is fiberglass and superhigh
density polyethelene is in places for flexibility and scratch
resistance/impact resistance. The outer hull is not pressure bounding. If
you want to know all the strengths, I can get out my design and calculations
and compare it to steel. I designed it for 500 ft, with a max operating
depth of 150 ft.
Remember some of the most flexible (from diffferent design points)materials
are composite designs.
Suds
________________________________________________________________________
Get Your Private, Free E-mail from MSN Hotmail at http://www.hotmail.com