September 8, 2023 at 3:27 pm
Bill Bulat
Ansys Employee

Yes, INISTATE is the command to use. I found this old MAPDL input file (pasted below) in my examples directory that illustrates usage. In this example, INISTATE is applied to solid elements, but it works for shells as well. With layered shells, you can apply different initial stresses to individual layers.

 

I forget whether or not this feature is natively exposed in Mechanical. If not, you'll need to use an APDL command object to implement it.

 

fini
/cle
 
/vup,1,z
/vie,1,1,1,1
/pnu,mat,1
/num,1
/gra,full
 
/sys,del *.png
 
 
C******************************************************
C*** PARAMETERS
C******************************************************
l=1000e-6
w=100e-6
 
t_Pd=5e-6
t_Cu=5e-6
 
E_Pd=110e9
nu_Pd=0.39
 
E_Cu=117e9
nu_Cu=0.34
 
sgma_Pd=1e6
 
 
C******************************************************
C*** GEOMETRY
C******************************************************
/prep7
 
vsel,none
bloc,,l,,w,,t_Cu
vatt,2,2,2
 
vsel,none
bloc,,l,,w,t_Cu,t_Cu+t_Pd
vatt,1,1,1
 
numm,kp,1e-8,1e-8
 
 
C******************************************************
C*** ATTRIBUTES, MESH
C******************************************************
et,1,185,,2 ! PALLADIUM ATTRIBUTES
mp,ex,1,E_Pd
mp,nuxy,1,nu_Pd
 
et,2,185,,2 ! COPPER ATTRIBUTES
mp,ex,2,E_Cu
mp,nuxy,2,nu_Cu
 
alls ! MESH
vplo
vmes,all
 
 
C******************************************************
C*** BCs
C******************************************************
alls
d,node(0,0,0),all
d,node(0,w,0),ux
d,node(0,w,0),uz
d,node(0,0,t_Pd+t_Cu),ux
 
 
C******************************************************
C*** Pd INITIAL STRESS
C******************************************************
inistate,set,dtyp,,stre
 
esel,s,mat,,1
inistate,define,,,,,sgma_Pd,sgma_Pd,sgma_Pd
 
fini
 
 
C******************************************************
C*** SOLVE
C******************************************************
alls
/solu
save
solv
fini
 
 
C******************************************************
C*** POST PROCESS
C******************************************************
/post1
 
/pbc,u,1
eplo
/sho,png $eplo $/sho,close $/wait,2
 
plns,u,z
/sho,png $plns,u,z $/sho,close $/wait,2
 
plns,s,x
/sho,png $plns,s,x $/sho,close $/wait,2
 
esel,s,mat,,1
plns,s,x
/sho,png $plns,s,x $/sho,close $/wait,2
 
esel,s,mat,,2
plns,s,x
/sho,png $plns,s,x $/sho,close $/wait,2