Message-ID: <360B831C.57E9@erols.com>
Date: Fri, 25 Sep 1998 07:48:44 -0400
From: "Jeffrey B. Chipetine" <abcrental@erols.com>
Reply-To: abcrental@erols.com
To: lancair.list@olsusa.com
CC: abcrental@erols.com
Subject: fibreglass and carbon fiber
Mime-Version: 1.0

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>>
Scott Dahlgren makes a very good point in the cautionary statement about
mixing materials. While the hope of the designer is always to achieve
the best of both without the drawbacks of either,  this is often an
evasive task, especially with carbon fibre! Depending on the modelus of
the fibres and the VERY INDIVIDUAL properties aquired with the
INDIVIDUAL reisins,  you could be setting the stage for a failure event. 
One of the most infamous large scale examples of catastrophic failure of
combined materials came about during the 1979 Fastnet Yacht race. EVERY
yacht (we're talking about professionally designed/extravagently custom
built, no expense spared) that had combined carbon and aluminum in the
rudder shafts failed when a severe storm ran over the fleet and
subjected these shafts to high loads.  It is interesting to note that
the rudder shafts were "designed" and expected to withstand these loads,
but as no one had ever tested the new and improved combination of alum
and carbon to failure, the high end of the envelope was unknown.  As
carbon was the new kid on the block at that time, it was thought that
the high strength and light weight would be "backed up" by using a known
material (alum) in combination.  15 men lost their lives when their
vessels couldn't take the strain. Yacht racing also showed that exotic
materials can be used with excellent results (carbon w/ kevlar, carbon
w/boron, etc).  The key for the high stress tests seems to be to find
materials that will work in tandem with a compatible reisin.  Carbon
qualities of high tensile strength can work against you when combined
with a "stretchy" reisin and then oriented so the load is tortional or
on the bias.  Combine both carbon and glass (E glass? S glass? or exotic
matrix?) with different reisins and you will aquire different
qualities.  Just remember to test a sample to failure under reasonably
controlled conditions (in all modes including tension, compression,
torque, as well as bending tests) prior to comitting yourself to the
marrige.  Regards to all and praise to Marv for this wonderful
opportunity...  Jeffrey B. Chipetine