Subject: Further FEA on George Mount
From: "Vern Stahlberger" <[email-masked]>
To: <[email-masked]>, "George Koenig" <[email-masked]>
Cc: "Vern Stahlberger" <[email-masked]>, "Douglas Toomey" <[email-masked]>
Date: Tue, 7 Oct 2003 14:36:30 -1000

As the pic shows, the load was applied to the mounting
surface for the X-Y Stage. The same surface was again
held fixed as in previous FEA Model. The force is again
160 lbs, acting in the -y direction (triad), also shown
by the blue arrows.

The color bar shows the displacement in the model.
The number cruncher came up with a max displacement
of .00226 inch. Stress is not of concern here.

By taking this number and knowing the distance to the
POM, you can calculate the angle through which the 
POM is rotated because of this displacement of .00226 inch

The situation modeled in the FEA is with the Telescope
pointing straight up. As you rotate the Telescope through
an axis that is coming out/in of the page of the pic, the
situation gets better. So, this is again a worst case situation,
but it happens to be also an often used position with the
Telescope.

Therefore, if we assume the distance from about the center of
the Acquisition Box to the POM to be 24 inches (a guess
right now) then the angle the POM would rotate, assuming
that the rest of the structure is not bending, is about 7 arc-sec

Now, one needs to figure out what this means in terms of
observing and tracking with varying integration times.

Vern