Subject: Re: [harryproa] Re: low cost carbon fiber
From: "Rob Denney" <>
Date: 5/22/2008, 10:18 AM


Thanks. You are absolutely correct. Every 2mms (.08") thickness of
uni, you should have a layer of off axis (+/-45 degrees) material
unless it is loaded purely in tension (guy wires for example). If
there are point loads, (deck bearings on unstayed masts for example)
then some material at 90 degrees is also a good idea. If the tube
sees twisting loads (rudder shafts for example), then more +/- 45 is

I was referring to shear strength as the strength required to resist a
scissors type cutting action. There is also sheer strength where two
l;ayers of material move relative to each other in the same plane,
which is a resin problem, and sheer strength as applied to a sheer web
on an I beam, which is all at +/-45 degrees.

On Thu, May 22, 2008 at 10:22 AM, <> wrote:
> In a message dated 5/21/2008 5:45:54 P.M. Central Daylight Time,
> writes:
> does impregnated perpendicularly laid tow of similar weight have the same
> mechanical characteristics as an impregnated woven fabric in terms of shear
> strength?
> NO!!!!!
> Uni will give you insane strength along your fiber axis. In off-axis loading
> it will fail if you look at it harshly. You need a layer of cloth laid at 45
> degrees to support your uni.
> Larry
> ________________________________
> Get trade secrets for amazing burgers. Watch "Cooking with Tyler Florence"
> on AOL Food.

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