Re: [ATM] Polishing / Figuring Simulator

[Richard <cnc@cncservo.co.uk>]

Hi matt,

Tuesday, May 9, 2006, 1:47:37 AM, you wrote:

m> Instead of calculating the pressure distribution , why not measure it ?
m> A modest 8-16 channel data acquisition system could do that , and it
m> wouldn't cost much .

I am currently looking at finite element analysis of a fixed
mirror with a lap resting on it at various radial positions.
Looking at the surface stress the one striking thing that jumps
out is how the stress soars at the very edge of the mirror as
soon as the lap starts to overhang. The edge stress is 7 or more
times higher than just an inch away on a 20 inch mirror.

Adding a chamfer actually raised the maximum stress but moved it
to the chamfer face, with an overall lowering of maximum stress on
the mirror surface. It was lowered still further by applying a
radiused fillet to the edge rather than a chamfer.

I'll try to put some results up on a web page when I've
finished.

-- 

Best regards,
  Richard in the UK


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