You can use Roark as a reference, as indicated above. The loaded case must be understood in addition to boundary control.
A round plate, simply supported at the circumference has maximum bending stress at the outer edge and maximum deflection at the centre. Assuming a uniform round plate of constant thickness and again, assuming a uniform pressure distribution across the wetted membrane then this becomes:
y = [-qa^4(5+v)]/[64D(1+v)] for q=pressure, a=radius and D=plate constant
M = [qa^2(3+v)]/16 for v=Poisson's Ratio
The plate constant is calculated as D=Et^3/[12(1-v^2) where E=Young's Modulus and t=plate thickness.
Finally, the stress is found as S=6M/(t^2).
Kenneth J Hueston, PEng
Principal
Sturni-Hueston Engineering Inc
Edmonton, Alberta Canada