More About Deformation of Plates
That question I asked yesterday about calculating deformation caused by load generated a lot of useful leads! A reader pointed me to this calculation website that appears to be about as closely matched to my needs as I can imagine. It calculates deformation for a circle that is supported by a ring at various radii of the circle. All you have to do is enter the force (which should include that generated by the plate itself), the radius of the circle, the radius of the support, the Young's modulus in gigapascals, and thickness of the plate, and it calculates the displacement in millimeters.
Now, three screws supporting this isn't quite the same as a uniform ring, but I suspect that it will be close enough for my purposes. I'm going to go a little thicker than absolutely required, just for that reason, but even for .09" thick aluminum, the displacement is in the hundredths of a millimeter area--or about .002". That's fine.