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Fiber Orientation
A material's contribution
to a structure is determined by its inherent strength and its resistance to
being dislodged from its intended position. Regardless of how enormous the
inherent strength of a material, it cannot contribute unless it is
secured well. Fiberglass is very strong, with a
tensile strength of somewhere between 20,000 and 40,000psi, depending on
construction. In Epoxy boards, it is held in place by the Epoxy resin with a
tensile strength of about 2000psi. That is only about 1/10th the strength of
the fiberglass! We need to make sure, then, that as the composite is
stressed, the fiberglass takes the load, and not the weaker resin. The only
way this is going to happen is if the fibers are aligned in the direction of
the load, and are straight. If the fibers run in a wiggely manner, the resin
will have to fail in order for the fibers to straighten and take a load. |
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Observe this length of 1/2" Spectra
yacht braid, with a breaking strength of 17,000#.
That is its potential strength.
Lying there all wiggely, I can pull with 1/2oz of
force and disturb it. All its potential strength is going to waste. |
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Now the line is straight, and try as I
might, the only thing I could disturb is the post the line is tied to
(because I eat right, and because the termites have been in that post for a
few years now) |
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marketed as "advanced CarbonTech",
very helpful, eh? |
this didn't work so good, either |
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