Mixing two materials

I'm trying to simulate the behavior of a model made of a material which is a mixture of two materials available in the library. The materials are mixed in unequal proportions.

I'm able to calculate the basic properties of the new material such as the density but properties such as elasticity matrix and coupling matrix I have no idea how to. Is there any way comsol can do the math for me and come up with all the properties that piezoelectric materials need? Please help.

Thank you