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## [Towertalk] Strength of fiberglass.

 To: [Towertalk] Strength of fiberglass. n4kg@juno.com (n4kg@juno.com) Thu, 28 Feb 2002 16:11:20 -0600
 ```WRONG !!! (see below) The maximum shear stress Tau (max) for a hollow tube is Tau (max) = 16 Mt x D / pi (D^4 - d^4) ... (4th power of D and d) where D is the Outside Diameter d is the Inside diameter Mt is the bending moment (I presume) It is clear that the greater the wall thickness, the greater the strength, which is maximum when d = 0 (solid rod). NOTE: MOST of the strength comes from the outer region of the tube and it is more 'effective' from a strength vs weight standpoint to go to a larger diameter thin wall tube than to increase the wall thickness. When d = 0.5 D, Tau = (1 - 0.0625 ) Tau (rod) = 93.75% of the strength of a solid rod. When d = 0.75 D, Tau = (1 - 0.3164) Tau (rod) = 68.36% of the strength of a solid rod. Tom N4KG On Thu, 28 Feb 2002 "Randy Williamson" writes: > Solid is not stronger than hollow as it was explained to me its about > surface area. What would be interesting is carbon fiber and epoxy > resin over a round mold. > > Randy > AC7NJ > ________________________________________________________________ GET INTERNET ACCESS FROM JUNO! Juno offers FREE or PREMIUM Internet access for less! Join Juno today! For your FREE software, visit: http://dl.www.juno.com/get/web/. ```
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