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Re: Bronze (One-legged Support) Horse Structure

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I also had this train of thought but did not do numbers.  You beat me to the draw!

Thor A. Tandy   P.Eng.,  MCSCE
Victoria, BC, Canada
e-mail: <vicpeng(--nospam--at)vtcg.com>

-----Original Message-----
From: Paul Feather <pfeather(--nospam--at)san.rr.com>
To: seaint(--nospam--at)seaint.org <seaint(--nospam--at)seaint.org>
Date: Tuesday, November 17, 1998 10:26 PM
Subject: Re: Bronze (One-legged Support) Horse Structure


>I don't think that a higher strength material will necessarily solve all
>your problems.
>
>I did some research on various steel alloys for a land speed record vehicle
>tubular frame, where lighter is definitely better. The higher strength
>materials provide a higher yield point, but contribute little to the
>stiffness of the structure. There is no substitute for basic section
>properties. None of the steel materials I could find would allow a reduction
>in tube diameter, and therefore shell size and air drag, without far greater
>negative performance and stability effects.
>
>Have you looked at the deflection of the sculpture? Assuming a fixed length
>between center point of attachment and point of fixity, and a constant
>moment, the deflection is dependent on only E and I.
>
>My experience is that stainless tends to have a slightly lower E than
>typical structural steels, and the drop from 2" dia. to 1.25" dia. reduces
>the I value by approx. 85%.
>
>Another issue to consider is the torsional effects of a good cross wind. The
>same 85% reduction in rigidity applies.
>
>IMHO, if the larger bar fits, you're better off.
>
>Paul Feather, P.E.