[Halld-pid-upgrade] PID Upgrade Meeting Tomorrow

[Matthew Shepherd]

Baptiste,

I agree that a meeting is probably not necessary.

Quick report from our end:  we are developing a test plan
to validate the vertical orientation.

An interesting observation thus far from John's FEA is
that in the vertical orientation the thing that breaks first
is not the window but the corner of the wedge that is
pushing on the window.  That is where the maximum 
internal material stress is.

There is some additional uncertainty in this depending
on how the wedge is bonded to the window, but we
are trying to formulate a worst-case scenario to test.
FEA of the worst-case scenario still shows a significant
safety factor.

Additional analysis also shows that almost no stress
is generated at bar-to-bar epoxy joints under pretty
significant g-load.  It is not obvious that trying to break
one of these apart with a prototype bar piece would be
useful.  (The systematic error in the test due to uncertain
strength in aged epoxy is likely to dominate any large
safety factor we would try to quantify.)

Therefore, we are considering adapting our test
procedure a bit to use both a real quartz window and
at least one real wedge (our initial plan used Al wedges
to load the window).

John is finalizing a written proposal for testing that
is informed by FEA and we'll circulate that.  Hopefully
we can get some feedback from Jerry and perhaps
Tim, if he has time.

Matt

---------------------------------------------------------------------
Matthew Shepherd, Associate Professor
Department of Physics, Indiana University, Swain West 265
727 East Third Street, Bloomington, IN 47405

Office Phone:  +1 812 856 5808

On Sep 11, 2014, at 9:03 PM, Baptiste Guegan <guegan at mit.edu> wrote:

> Dear all,
> 
> we have made some progress on several points, but not enough new material to actually have a meeting for that.
> I am in contact with Jerry to discuss the results with the water and the 3 segments mirror. I have also contacted a company for the coating of the mirrors. So, several things are in progress, but the physics results haven't evolved too much since last meeting.
> 
> So except if somebody would like to discuss specifically something, I propose to have our next meeting in two weeks.
> 
> Best
> Baptiste
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