I’ve always used symmetrical composites below and above the core and achieved fine results, typically using triaxial glass and three inch wide strips of 9 oz uni carbon. I only heat from the bottom and the skis remain in the press after curing until the whole thing cools down to ambient temperature.
On my next pair I wish to increase the camber by 3-4mm still using my existing press form.
Curious to know what the effect of an asymmetrical layup coupled with asymmetrical heating (bottom only) will be. Assuming the composite plan is one layer of 22 oz triaxial glass on both sides of the core. If a wide strip of unidirectional carbon fiber is added only below the core, will the result be increased or reduced camber?
I’ve searched the forum and can’t find a definitive answer. I don’t want to waste time and materials performing a test layup if I don’t have to.
Cheers,
-S
Asymmetrical layup and the effect on camber
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twizzstyle
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Graphite fibers alone have a negative thermal expansion coefficient - that is to say that they contract with heat, and expand with cooling. Based on that, adding a layer only below should theoretically decrease your camber (as it cools the CF fibers will expand on the bottom of the core).
But, with building by hand there are so many other variables, reality might be different. It's tough to say what the relative thermal expansion/contraction of the CF is compared with the rest of the composite (the fiberglass, the epoxy, the core). Unfortunately the only way to definitively know, is to test it and see what happens.
But, with building by hand there are so many other variables, reality might be different. It's tough to say what the relative thermal expansion/contraction of the CF is compared with the rest of the composite (the fiberglass, the epoxy, the core). Unfortunately the only way to definitively know, is to test it and see what happens.
Ya, I figured I would probably have to set up a test. But if someone has already made an asymmetrical layup and achieved more or less camber than expected that would be good information.
As for carbon fiber CTE my research is inconsistent. Seems like it can be positive or negative depending on the source and fiber quality.
By the way, my most recent build has a symmetrical layup with 10 oz warp uni E-glass and 12 oz biaxial carbon (45). Wow, these are torsionally very stiff, just what I intended for a fat carving ski with 20 meter side cut radius (98 mm under foot).
-S
As for carbon fiber CTE my research is inconsistent. Seems like it can be positive or negative depending on the source and fiber quality.
By the way, my most recent build has a symmetrical layup with 10 oz warp uni E-glass and 12 oz biaxial carbon (45). Wow, these are torsionally very stiff, just what I intended for a fat carving ski with 20 meter side cut radius (98 mm under foot).
-S