To answer on your Question read the following:

1- You should divided the model into smal areas if you used 2-D FE ( or small volums for 3-D FE) using the do loop in APDL (i.e. A1- A2- A3- ......etc.).

* Write a  subrtine at the bigining of input data file to calculat E and Possions ratio (you can see the equations used for E and possions ratio in my papers H. s. Hedia) using the same do loop  as in areas (i.e. E1- E2- E3- ......etc.).

The following subrtine was used to calculate E and Possions ratio for one of my article and to assist each E to each type of material and each Area:-

x=0.5

m=1.0

n0=m

z=m

a=0.1

Em=40e3

Ec=110e3

nm=0.3

nc=0.3

H=9

I=2

*DIM,vm,,183

*DIM,vc,,183

*DIM,n,,183

*DIM,p0,,183

*DIM,E0,,183

*DIM,E,,183

*DO,H,0,9.0,.05

I=I+1

vm(I)=(H/9)**m

vc(I)=1-vm(I)

n(I)=nm*vm(I)+nc*vc(I)

p0(I)=a*((H/9)**n0)*(1-(H/9)**z)

z1=((vm(I))**(2/3)-vm(I))

z2=(Ec+(Em-Ec)*z1)

E0(I)=Ec*(Ec+(Em-Ec)*(vm(I))**(2/3))/z2

z0=(8*(1+n(I))*(23+8*n(I)))

z3=(p0(I)*(5+8*n(I))*(37-8*n(I)))/z0

E(I)=(E0(I)*(1-p0(I)))/(1+z3)

*ENDDO

*DO,I,1,183

  ET,I,82

  KEYOPT,I,3,1

*ENDDO

*DO,I,3,183

  MP,EX,I,E(I)

  MP,NUXY,I,n(I)

*ENDDO

MP,EX,1,110e3               !dental implant

MP,NUXY,1,0.3

MP,EX,2,17e3                !cortical bone

MP,NUXY,2,0.3

Refrences

1.        Hedia H.S and Mahmoud Nemat-Alla “Design Optimization of Functionally Graded Dental Implant” J. Bio-Medical Materials and Engineering. Vol 14, No.2, pp 133-143, An International Journal, Japan.

2.        Hedia H.S, "Effect of cancellous bone on the Functionally Graded Dental Implant Concept", J. Bio-Medical Materials and Engineering, Vol. 15, No. 3, 2005, pp. 199-209, An International Journal, Japan.

3.        Hedia H.S, M.A. Shabara, T.T. El Midany and N. Fouda "Improving the Performance of the Cementless Metal-Backed Acetabular Cup Prostheses through Functionally Graded Material"  8th International Conference on Production Engineering, Design and Control (PEDAC), Alexandria University, 2004, Alexandria, Egypt.

4.        Hedia H.S, M.A. Shabara, T.T. El Midany and N. Fouda "A method of material optimization of cementless stem through functionally graded material", International Journal of Mechanics and Materials in Design, Vol. 1, (2004), pp. 329-346.

5.        Hedia H.S."Design of Functionally Graded Dental Implant in the Presence of Cancellous Bone"J Biomed Mater Res Part B: Appl Biomater, Vol. 75B, (2005), pp. 74–80,  An International Journal, USA

6.        H. S. Hedia, "Comparison of One-Dimensional and Two-Dimensional Functionally Graded Materials for the Backing Shell of the Cemented Acetabular Cup", Journal of Biomedical materials Research Part B: Applied Biomaterials, Vol. 74B, Issue 2, (2005), pp. 732-739. An International Journal, USA

7.        Hedia H.S, M.A. Shabara, T.T. El Midany and N. Fouda. "A new design of a cementless hip stem using one and two-dimensional functionally graded materials" International Conference on Production Engineering and Design for Development, PEDD7 to be held in Cairo, Egypt during the period 7-9 February 2006.

8.        Hedia H.S, M.A. Shabara, T.T. El Midany and N. Fouda., “Improved Design of Cementless Hip Stems Using Two-Dimensional Functionally Graded Materials”, J Biomed MaterRes Part B: Appl Biomater 79B: 42–49, 2006,An International Journal, USA

9.      Hedia, H. S. and Fouda, N, "Design Optimization of Hip Prosthesis Coating using Functionally Graded Material "Computational Materials Science 87 (2014) 83–87

10.      H.S. Hedia, S.M. Aldousari, A.K. Abdellatif, N. Fouda " A new design of cemented stem using functionally graded materials (FGM)" Bio-Medical Materials and Engineering Volume 24, Number 3 / 2014

Yes, equivalent modulus of elasticity was used to solve the problems.

To answer on your Question read the following:

1- You should divided the model into smal areas if you used 2-D FE ( or small volums for 3-D FE) using the do loop in APDL (i.e. A1- A2- A3- ......etc.).

* Write a  subrtine at the bigining of input data file to calculat E and Possions ratio (you can see the equations used for E and possions ratio in my papers H. s. Hedia) using the same do loop  as in areas (i.e. E1- E2- E3- ......etc.).

The following subrtine was used to calculate E and Possions ratio for one of my article and to assist each E to each type of material and each Area:-

x=0.5

m=1.0

n0=m

z=m

a=0.1

Em=40e3

Ec=110e3

nm=0.3

nc=0.3

H=9

I=2

*DIM,vm,,183

*DIM,vc,,183

*DIM,n,,183

*DIM,p0,,183

*DIM,E0,,183

*DIM,E,,183

*DO,H,0,9.0,.05

I=I+1

vm(I)=(H/9)**m

vc(I)=1-vm(I)

n(I)=nm*vm(I)+nc*vc(I)

p0(I)=a*((H/9)**n0)*(1-(H/9)**z)

z1=((vm(I))**(2/3)-vm(I))

z2=(Ec+(Em-Ec)*z1)

E0(I)=Ec*(Ec+(Em-Ec)*(vm(I))**(2/3))/z2

z0=(8*(1+n(I))*(23+8*n(I)))

z3=(p0(I)*(5+8*n(I))*(37-8*n(I)))/z0

E(I)=(E0(I)*(1-p0(I)))/(1+z3)

*ENDDO

*DO,I,1,183

  ET,I,82

  KEYOPT,I,3,1

*ENDDO

*DO,I,3,183

  MP,EX,I,E(I)

  MP,NUXY,I,n(I)

*ENDDO

MP,EX,1,110e3               !dental implant

MP,NUXY,1,0.3

MP,EX,2,17e3                !cortical bone

MP,NUXY,2,0.3

Refrences

1.        Hedia H.S and Mahmoud Nemat-Alla “Design Optimization of Functionally Graded Dental Implant” J. Bio-Medical Materials and Engineering. Vol 14, No.2, pp 133-143, An International Journal, Japan.

2.        Hedia H.S, "Effect of cancellous bone on the Functionally Graded Dental Implant Concept", J. Bio-Medical Materials and Engineering, Vol. 15, No. 3, 2005, pp. 199-209, An International Journal, Japan.

3.        Hedia H.S, M.A. Shabara, T.T. El Midany and N. Fouda "Improving the Performance of the Cementless Metal-Backed Acetabular Cup Prostheses through Functionally Graded Material"  8th International Conference on Production Engineering, Design and Control (PEDAC), Alexandria University, 2004, Alexandria, Egypt.

4.        Hedia H.S, M.A. Shabara, T.T. El Midany and N. Fouda "A method of material optimization of cementless stem through functionally graded material", International Journal of Mechanics and Materials in Design, Vol. 1, (2004), pp. 329-346.

5.        Hedia H.S."Design of Functionally Graded Dental Implant in the Presence of Cancellous Bone"J Biomed Mater Res Part B: Appl Biomater, Vol. 75B, (2005), pp. 74–80,  An International Journal, USA

6.        H. S. Hedia, "Comparison of One-Dimensional and Two-Dimensional Functionally Graded Materials for the Backing Shell of the Cemented Acetabular Cup", Journal of Biomedical materials Research Part B: Applied Biomaterials, Vol. 74B, Issue 2, (2005), pp. 732-739. An International Journal, USA

7.        Hedia H.S, M.A. Shabara, T.T. El Midany and N. Fouda. "A new design of a cementless hip stem using one and two-dimensional functionally graded materials" International Conference on Production Engineering and Design for Development, PEDD7 to be held in Cairo, Egypt during the period 7-9 February 2006.

8.        Hedia H.S, M.A. Shabara, T.T. El Midany and N. Fouda., “Improved Design of Cementless Hip Stems Using Two-Dimensional Functionally Graded Materials”, J Biomed MaterRes Part B: Appl Biomater 79B: 42–49, 2006,An International Journal, USA

9.      Hedia, H. S. and Fouda, N, "Design Optimization of Hip Prosthesis Coating using Functionally Graded Material "Computational Materials Science 87 (2014) 83–87

10.      H.S. Hedia, S.M. Aldousari, A.K. Abdellatif, N. Fouda " A new design of cemented stem using functionally graded materials (FGM)" Bio-Medical Materials and Engineering Volume 24, Number 3 / 2014

Did you already extract material properties throughout the grade? If so, How!?

İ think this article could help:

https://www.researchgate.net/publication/332990860_Modeling_and_Buckling_Analysis_of_Rectangular_Plates_in_ANSYS