Hollow glass fiber fabric?

[vol]

Hi,
I'm new in this forum, I'm building kiteboards but using same technology like ski or snowboards. I just have quiestion abaut glass fibre.
I find some hollow glass at the R&G internet shop shop.r-g.de , fibre have very interesting specification, someone one tried this?
Info from annotation,
Hollow glass fibre fabric 216 g/m²
H-glass is a lower density fibre in comparison with a "solid" E-glass or S-2 Glass, thus reducing the overall weight of cured laminates by up to 40 %! H-glass is more elastic, has higher compression strength and specific strength characteristics compare to "solid" E-glass fibres.

[doughboyshredder]

Interesting stuff.

Already being used for windsurf boards. http://www.witchcraft.nu/techinfoseries.php

I am sure you could use it for kite boards.

[fa]

never tried that glass
i use rg products and they are top quality though
right now i have 5 lit of their resine seating next ro me
a cheap way to reduce weight in a kiteboard is to skip some plastics (topsheet and pe base ie) and a couple or 2 of inserts
you ll easy end way lighter than the industry standard that way
fins are quite heavy too

[vol]

Thanks for answer guys
Kiteboard 40% less laminate weight is a lot, I can save 400g at list, sounds good. I will try this

[White Thrash Wednesday]

Hello, the hollow glass is used by HEAD. From their website:

"AIRCOAT
Super Light + Super Strong = Super Agile

While everybody is trying to make the core of their skis lighter, we decided to put air in the surrounding fiberglass. AIRCOAT means our fibers are hollow, not only making our 08.09 freeride and multi condition skis super light, but extremely agile and strong at the same time. This technology, also used in the aerospace industry, is the main reason, why AIRCOAT equipped skis like Jon Olsson’s new pro model or our XENON line will most probably be
the lightest skis on the market next year."

the r-g.de site states:
"H-glass is a lower density fibre in comparison with a "solid" E-glass or S-2 Glass, thus reducing the overall weight of cured laminates by up to 40 %! H-glass is more elastic, has higher compression strength and specific strength characteristics compare to "solid" E-glass fibres."

I`m not to convinced about this... Looks like marketing to me. The strength and stiffness depend on the cross section area of the fiber among other things, and if it is hollow you need a higher amount of fibers to get the same total cross section area of the fibers in your laminate.

So the fiber itself is lighter (since it contains air) and having less material when compared to a solid fiber, making a lighter laminate. Sort of saying you get a lighter laminate if you use a 200g/m^2 instead of a 300g/m^2 reinforcement. The laminate will be lighter, but not as stiff or strong as a the 300g/m^2 laminate.

They say it has "higher" specific strength than solid E-glass? If they use regular S-glass this statement is also true.

Edit: In the data sheet http://shop.r-g.de/out/media/td_en_hollow_glass.pdf they compare composites there is not to much info. They compare with a E-glass composites and there is no mechanichal properties for strength and stiffness comparisons.

Just my thoughts... :-)
Does anyone have any other ideas or have done some actual testing, comparing with regular E or S-glass reinforcement, to the hollow material? Would be cool to get some more info on this matter. :-)
/Johan

[doughboyshredder]

I`m not to convinced about this... Looks like marketing to me. The strength and stiffness depend on the cross section area of the fiber among other things, and if it is hollow you need a higher amount of fibers to get the same total cross section area of the fibers in your laminate.

So the fiber itself is lighter (since it contains air) and having less material when compared to a solid fiber, making a lighter laminate. Sort of saying you get a lighter laminate if you use a 200g/m^2 instead of a 300g/m^2 reinforcement. The laminate will be lighter, but not as stiff or strong as a the 300g/m^2 laminate.

They say it has "higher" specific strength than solid E-glass? If they use regular S-glass this statement is also true.

I tend to believe it. Hollow steel is stronger than solid steel. I am not an engineer so I can't say exactly why, but I do know that a solid piece of steel is much easier to bend than tube steel. Build a frame out of solid steel and it will bend so much that it would be useless. Build the same frame out of tube steel and it will be as rigid as concrete.

[Brazen]

My bet is it soaks up an assload of resin.

[vol]

I got answer from hollow glass seller R&G and this cause even more confusion

Question to R&G

I using for my lamination about 500-600g/m2 couple layers E-glass fibre, what H-glass weight I have to use for same laminate strength?

Answer

thank you for your enquiry. Should be around the same weight. H-glass has a significantly lower density only in high fibre volume fractions < 60 %. Strength is more or less the same as E-glass.

so.. now really lot of mess... I wanna make test between hollow and solid, how to?

[vol]

http://i638.photobucket.com/albums/uu10 ... s/TUBE.jpg

[doughboyshredder]

huh.

progressively lesser strength as it approaches the center axis. Hence, solid is often only slightly stronger in deflection than decent hollow tube.....despite adding much greater weight