Just run a 2 stepped analysis.
LS1: First step
Apply forces whatever
ALLS
SOLVE
LS:2 Change Mat.Properties
MPDATA,EX,,,,
MPDATA,NUXY,,,,
ALLS
SOLVE
The mat.prop change is not an approved strategy but works fine by me. If its a large analysis u can save restart info and start with whatever properties u want in step 2..
(RESCONTROL, ANTYPE)
BrgDs OddEinar