## General Mechanical

Topics relate to Mechanical Enterprise, Motion, Additive Print and more

#### Apply Intrinsic stress to circular shell element

• Tanmay Konnur
Subscriber

How do I apply compressive and tensile intrinsic stress (on separate occasions) to a circular shell element such that it is uniform across the circular shell element. I do not want a gradient. Is INISTATE command applicable in this case?

• 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******************************************************
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