How to determine the flexural rigidity of a composite

kaizen.moto

Hi there,

I need help about how to solve the flexural rigidity (D) of a composite. For instance, if I have two plies of a plate each with different material properties, i.e. ply 1 has different Young modulus from ply 2. Therefore, how can I determine the value of the overall D of the plate.
How can I smear the D?

Example:

ply 1 has E1 = 200 MPa, E2 = 30 MPa and v = 0.2
ply 2 has E1 = 400 MPa, E2 = 40 MPa and v = 0.3

using the D = Eh / 12(1-v^2), how can I smear the two different properties into a single value of D?

Please let me know. Thanks