[ATM] Re: Mirror cells - some professional literature and ideas foramateurs

[tkrajci at san.osd.mil (Tom Krajci)]

>From: "Steve Houlihan" <SHO@SURFNETUSA.COM>

>> My $64 question:  Can I make whiffletree cells for large/thin mirrors
>> that serve as both axial and lateral support...in other words combine
>> the two functions of axial and lateral support in one mechanical
>> structure.  

>...In my case I got worried about the large moment applied to the back
of >the mirror....

>...So, from this limited study of the problem, I suggest a whiffletree
with >a ball joint pivot that is forward of the mounting surface and
resides in a >recess in the back of the mirror.  Piece of cake!

>...I sure I can come up with a few more crazy ideas if I read some
more.

I am interested in a simpler, hopefully adequate solution.  Instead of
'long' moment arms (pivots over an inch behind the mirror's face,
etc.)...'flatten' or 'lower the profile' of the mirror cell and pivot
locations.  It does not bring the moments to zero...but reduces them by
some amount.

For example, see:
http://overton.tamu.edu/aset/krajci
specifically:
http://overton.tamu.edu/aset/krajci/cell-beam/cell-beam.htm

The 24 and 48 point cells...have several 'stacks' of beams on top of
each other.  That puts some of the pivots fairly far from the mirror's
rear surface...generating considerable moments.  However, if you
bend/shape/profile the beams...you can position each pivot point awful
close to the mirror's back face.  (I suppose the same could be done with
whiffletree cells with triangles.)  That will help reduce moments.  Is
that a step in the right direction?  Is it good enough?

Tom Krajci
Tashkent, Uzbekistan


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