PlaneStress

I have alreday made a simple isotropic plasticity for 3D element and that worked well, but it is becoming compless for me to modify the subroutine to fit for PlaneStress, I made the following modification:# 

CCCC   in the beginning, 

 stressNew(i,3)=0

 stressNew(i,5)=0

 stressNew(i,6)=0

CCCC  at the end:

  StrainInc(i,3)= dEpsPla33+fac4*(StrainInc(i,1)+StrainInc(i,2)
        -dEpsPla11-dEpsPla22)

where,   dEpsPlaii is increment of plastic strain ii which are calculated before, and fac4 is xnu/(xnu-one).