Model FGM in Ansys
 

I've been trying to model Al2O3/Al FGM in Ansys. But, no luck with it. I have found an ICME paper (check out the link) where a simplified equation is provided to model this FGM. But, I wonder how to use this equation to generate FGM?? I have never used usermat of Ansys. I Do not even know how to define "user defined material" in Ansys. Please, help me.

http://www.buet.ac.bd/me/icme/icme20...011-AM-015.pdf