Re: Need formula describing a drumhead membrane under partial vacuum

Since we can assume that the loading is uniform (vacuum) and that the edges 
of the membrane are sealed and clamped (else there won't be a vacuum), then 
the analysis is the classical one found in S. Timoshenko's book "Strength 
of Materials" LC 55-6497 third edition (1955) Van Nostrand

Look it up. I can't type formulae in emails ! If I remember rightly the 
form is somewhat quadratic, so the deformation will be paraboloidal -ish, 
egde effects not withstanding.

Steve