[ATM] Second Thoughts on Mirror Support

[stuart452 at earthlink.net (Stuart Hutchins)]

Mark,

How did Nils Olof Carlin get the sling force (when the sling pulling at a
slight up-angle) into Plop?

Just for rough numbers, could the pivot points be offset to produce uneven
supports forces similar to what would be produced by the sideways component
of mirror weight?  The resulting pattern would not be rotationally
symmetric.  But I see on your pages of 12 point patterns some systems that
are not symmetric. Number 12j, in particular, has two short vertical bars at
the top and bottom.  Can the pivots of those bars be moved from 50% up to 67
or 75% ?  That would produce the "S" bending forces.

The goal would not be an exact deformation plot for Steve's cell, but a
general idea of how bad the "S" shape becomes.

Regards,

Stuart Hutchins


----- Original Message -----
From: "Mark Holm" <mdholm@telerama.com>
To: "Stuart Hutchins" <stuart452@earthlink.net>
Cc: <atm@atmlist.net>
Sent: Thursday, February 05, 2004 6:48 PM
Subject: Re: [ATM] Second Thoughts on Mirror Support


>
>
> Stuart Hutchins wrote:
>
> >
> >The original poster, Steve Houlihan, has the mirror cell with the
ball-joint
> >pivots behind the whiffle triangles, not a solid plate.  Therefore his
> >forces (minus ball-joint sticktion) will be transmitted right through the
> >three compliant RTV pads to produce uneven support forces at the mirror.
> >These forces can be easily estimated as I outlined in my first post.
Then
> >PLOP can show how serious the deformation is.
> >
> Umm, yes I guess you are right at least to a first approximation, the
> forces will be transmitted through the RTV..  I'm not sure about using
> Plop to model it though.  I don't know of a mode where you can put
> arbitrary forces on the supports in Plop.  It usually assumes that the
> weight of the mirror is the only source of primary forces.  Maybe I am
> missing something though.
>
> Mark Holm
>
>
>