Rick Girard wrote:
Paul, All too true, but these were generally cast of Nylon 6/6 or some
other chopped glass filled resin. Just like chopper gun shot composite
parts, the resin to glass ratio was wrong and the parts had a limited
life span. Get the resin to synthetic ratio to the proper level and use
a woven material instead of loose filler and the life should improve
greatly.
Rick Girard
Sure at normal temperature. We are talking temperatures close to the
melting point of the resin. Even special high temp epoxy
only goes to 300 F. I'll bet the strength is way down at 200 F
Aluminum loses half its strength at only 500 F.
Paul Lamar
Paul, Also true, but following the resin manufacturers to "heat threat" the finished parts (raise T sub g) and the strength will
go up as will the temperature at which deformation will occur. Some resin formulations do this better than others and it's
important to match this characteristic to the performance desired. For instance, parts made with Saf-T-poxy can be softened with
heat and reformed to straighten a trailing edge, say, and it can be repeated many times.
Parts made with Aeropoxy will allow
this once and the extra hardness is then set into the part. This was explained in detail on the canard.com forum by epoxy guru
Gary Hunter and the text can be found in the message archives.
Rick Girard
They can make all sorts of claims for the stuff and prove it when it is new but ten years
down the road it may act entirely differently. NASA places the shuttle tires
in a vacuum chamber and heats them up to artificially age them as I recall.
The thing about organic compounds is they tend to out gas. We have all smelled
this happening inside a new car. That distinctive odor is all the plastic trim
and upholstery out gassing. The same thing goes for recently cured fiberglass. If you
can smell it it is changing.
Paul Lamar
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