Re: ATM Re: Structural truss analysis - initial findings

["Ken Hunter"<kb7h@onemain.com>]

On Thu, 26 Dec 2002 18:02:03 +0500 Tom Krajci <tkrajci@san.osd.mil> wrote:

> Hmmmm...looking a the Kriege/Berry book, the
> chapter on engineering
> concepts/truss stiffness, etc....it seems to be
> wrong.  They mention 50%
> larger truss tubes are 5 times stiffer (they
> are, as individual
> members)...but according to the above
> equation...only 50% stiffer as an
> *entire truss system*.
> 

Could the difference be that in the first instance you are looking at
deflection of the tube from it's axis, while in the truss arrangement you are
mainly looking at compression and extension along the axis? 

I intuitavely *think* the truss would be more than 50% stronger if everything
else were kept the same and the tube diameter were increased by 50%.  

But... 

I wonder if the gain in stiffness is outweighed (grin) by the increase in
weight of the truss or if larger gains in stiffness can be obtained by
widening the base of the truss and keeping the tubing the same.

Just a thought.

Ken Hunter





Happy Grinding,
Ken Hunter

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