[TowerTalk] Which Vertical is More Robust ?

[jimlux]

On 1/1/20 11:35 AM, Richard (Rick) Karlquist wrote:
> Extreme tapering has its limits.  At some point, the vertical
> will not stand up straight even in the absence of wind.  The top will
> always bend over at some azimuth.  Now if you take the top
> portion only of this vertical off and ground mount it, you will find
> that it will stand up straight.  I don't know this from theory,
> or even software.  Rather: actually building it.  Who knew?

It's probably because it's not perfectly symmetrical, and as soon as it 
bends a little, will reach some sort of equilibrium.  That asymmetry 
could be from, say, the sun shining on one side and the differential 
thermal expansion.

You could probably solve it as a differential equation for an idealized 
uniform tube - it would be similar to the deflection of a cantilever 
beam with a uniform load (where the load comes from differential expansion).




> 
> This would probably be a great interview question for an ME...
> 


It would be an interesting question - especially to see if they have an 
analytical solution or immediately jump to an FEM approach.