Looking for an equivalent indentation modulus for composite

Dear all (and Prof. Ciavarella, if you can see this),

I am looking for an equivalent indentation modulus for orthotropic composite materials in a contact problem. Does anybody has any reference or equation to get the value?

I have come across a paper by Prof. Ciavarella titled 'The general 3D Hertzian contact problem for anisotropic materials' from Key engineering materials yr:2002 vol:221 pg:281 -292. In the paper, it is mentioned that the modulus can be approximated by 1/pi*h0. h0 is the first Fourier series term in the Green's function. I wonder if anyone know the explicit equation for calculating h0.

Any help is much appreciated. Thanks.

Regards,

Khong