[Rhodes22-list] FRP strengthening/ slide hatch

[Roger Pihlaja]

Lou,

By any chance, could you send me a picture of the crack?  It's hard to
recommend a remedy without seeing the problem.

Roger Pihlaja
S/V Dynamic Equilibrium

----- Original Message -----
From: "Lou Rosenberg" <lsr3 at MAIL.nyu.edu>
To: "The Rhodes 22 mail list" <rhodes22-list at rhodes22.org>
Sent: Tuesday, September 07, 2004 1:20 PM
Subject: Re: [Rhodes22-list] FRP strengthening/ slide hatch


>   Roger,
>    I saved this reply b/c it applies to my sliding hatch which
> definitely has a visible crack in the  leading edge ( fore) .   My
> seat was poor judgement and inexperienced eyes on FRP. I have since
> been corrected by ( God ) of all folks, and Don Casey helped too
> along with  yourself!
> Would you advise doing the strengthening on the hatch  with thickened
> epoxy as you stated below a few wks ago?
>   thanks
> Lou
>
>
>
> Lou
>
> >
> >If there are visible cracks or other flaws in the FRP composite
underneath
> >the cockpit seat; then, you will have to do something ASAP.  Failure of
an
> >FRP composite structure is a cumulative damage sort of phenomena.  Every
> >time you step on the seat & hear a "crack", that is the sound of some
glass
> >fibers snapping or the bond between some of the glass fibers and the
> >polyester resin substrate failing.  FRP composites do not "heal"
themselves.
> >Under moderate overload, they just progressively fail one fiber or one
> >fiber/substrate bond at a time until the remaining structure is too weak
to
> >support the load.  Then these materials fail catastrophically in a sudden
> >brittle manner.  If the cracks are visible on the surface; then, you may
be
> >able to reinforce the structure by injecting unthickened epoxy into the
> >cracks with a syringe.  Have someone stand on the weak spot while you
inject
> >the epoxy as deeply into the opened surface cracks as possible.  Then,
have
> >your assistant get off the seat.  Repeating this several times will work
the
> >epoxy up into the FRP composite structure out to the tip of the
developing
> >crack.  After the epoxy hardens inside of the FRP composite structure,
this
> >should arrest the crack development.  However, you will still need to
> >reinforce the cockpit seats or this sort of failure will start occuring
> >again.
> >
> >Roger Pihlaja
> >S/V Dynamic Equilibrium
> >
> >----- Original Message -----
> >From: "Lou Rosenberg" <lsr3 at MAIL.nyu.edu>
> >To: "The Rhodes 22 mail list" <rhodes22-list at rhodes22.org>
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