Learning Forum

[Caterina Azais]

Hi everyone! 

I am new to ansys and have been really struggling to get my code working.... I want to simulate the voltge output of a dielectic material under a uniform pressure acting on the top lectrode. Can someone please please please help me? Thanks !

! Geometry

l = 5e-3 ! beam length, m

w = 5e-3 ! electrode width, m

t = 100e-6 ! thickness, m

 

!Loading

PRES= 10000 !pressure loading, Pa

 

! Material properties

Y = 140e9 ! Young modulus, Pa

mu=0.358 ! Poisson ratio (nearly incompressible rubber)

eps=8.17 ! electrical permittivity, relative

eps0=8.854e-12 ! free-space permittivity, F/m

 

/VUP,1,z

/VIEW,1,1,1,1

 

 

/PREP7

ET, 1, 5, 3

 

! == Material parameters

! -- Elastic coefficients, MPa

c11 = 209.71e9

c12 = 121.14e9

c13 = 105.36e9

c33 = 210.9e9

c44 = 42.5e9

c66 = 44.28e9

 

tb,ANEL,1

tbdata, 1, c11, c12, c13

tbdata, 7, c11, c13

tbdata, 12, c33

tbdata, 16, c66

tbdata, 19, c44

tbdata, 21, c44

 

! -- Piezoelectric coefficients, pC/um2

e13 = -0.61

e33 = 1.14

e15 = -0.59

 

tb,PIEZ,1

tbdata, 3, e13

tbdata, 6, e13

tbdata, 9, e33

tbdata,14, e15

tbdata,16, e15

 

! -- Dielectric constants

emunit,EPZRO,8.854e-6 ! pF/um

mp,PERx,1, 7.57

mp,PERy,1, 7.57

mp,PERz,1, 8.31

 

! -- model and mesh block

block,-l/2,l/2,-w/2,w/2,0,t

 

! Set the merging tolerance (adjust as needed)

KETOL = 1.0e-5

vmesh,1

 

 

! Structural BC - fix the displacement of bottom face

nsel,s,loc,x,-l/2

d,all,ux,0

nsel,r,loc,y,-w/2

d,all,uy,0

nsel,r,loc,z,0

d,all,uz,0

nsel,all

 

! Electrical BC

nsel,s,loc,z,0

nsel,r,loc,x,-l/2,l/2

nsel,r,loc,y,-w/2,w/2

cp,1,volt,all

ng=ndnext(0) ! ground node

 

nsel,all

nsel,s,loc,z,t

cp,2,volt,all

nl=ndnext(0) ! load node

nsel,all

 

/SOLU

antype,static

cnvtol,f,1,1.e-6

cnvtol,amps,1,1.e-6

cnvtol,volts,1,1.e-6

d,ng,volt,0 !put ground node to zero volts

nsel,s,loc,z,t

nsel,r,loc,x,-l/2,l/2

nsel,r,loc,y,-w/2,w/2

sf,all,PRES,0  !apply pressure

 

nsel, all

solve

fini

 

/POST1

nsel,all

pldisp,1 ! display deformed/undeformed shape

andscl ! animate deformed/undeformed shape

nsel,s,loc,x,l/2

nd=ndnext(0) ! pick node for display

nsel,r,node,,nd

prnsol,epel ! print strain

prnsol,volt ! print voltage

nsel,all

fini

 

 

 

[Erik Kostson]

 

Hi

The restrains, do not seem to be very well defined perhaps – but one issue is the pressure load (sf) sf,all,PRES,0 applies a 0 pressure which is not what one uses as a load (zero loads), and it applies it to the sides as well as the top – 

so go through the command reference (e.g., sf command) and some simple apdl examples and then try to understand what you want to do and then how to do it using apdl – I would suggest to do this in workbench, where it is much easier.

SF (ansys.com)

Finally go through one of our courses:

https://www.youtube.com/playlist?list=PLtt6-ZgUFmMKFfbOBhmCwG30KIVyvhDop

 

If you are not able to open the links, refer to this forum discussion: How to access the ANSYS Online Help

Guidelines for Posting on Ansys Learning Forum

Hope that helps

 

[Caterina Azais]

thank you so much, that seems to be making much more sense now... I have changed the code as follows, however when i print the PRNSOL commands it says that the S, D, .. data are not available and hence its ignored. What is the problem? Thank you !

 

! Geometry

l = 5e-3 ! beam length, m

w = 5e-3 ! electrode width, m

t = 100e-6 ! thickness, m

 

! Material properties

Y = 140e9 ! Young modulus, Pa

mu=0.358 ! Poisson ratio (nearly incompressible rubber)

eps=8.17 ! electrical permittivity, relative

eps0=8.854e-12 ! free-space permittivity, F/m

 

/VUP,1,z

/VIEW,1,1,1,1

 

 

/PREP7

ET, 1, 5, 3

 

! == Material parameters

! -- Elastic coefficients, MPa

c11 = 209.71e9

c12 = 121.14e9

c13 = 105.36e9

c33 = 210.9e9

c44 = 42.5e9

c66 = 44.28e9

 

tb,ANEL,1

tbdata, 1, c11, c12, c13

tbdata, 7, c11, c13

tbdata, 12, c33

tbdata, 16, c66

tbdata, 19, c44

tbdata, 21, c44

 

! -- Piezoelectric coefficients, pC/um2

e13 = -0.61

e33 = 1.14

e15 = -0.59

 

tb,PIEZ,1

tbdata, 3, e13

tbdata, 6, e13

tbdata, 9, e33

tbdata,14, e15

tbdata,16, e15

 

! -- Dielectric constants

emunit,EPZRO,8.854e-6 ! pF/um

mp,PERx,1, 7.57

mp,PERy,1, 7.57

mp,PERz,1, 8.31

 

! -- model and mesh block

block,-l/2,l/2,-w/2,w/2,0,t

 

! Set the merging tolerance (adjust as needed)

KETOL = 1.0e-5

vmesh,1

 

! Structural BC

nsel,s,loc,z,0

d, all, volt, 0

d,all,ux,0

d,all,uy,0

d,all,uz,0

nsel,all

 

nsel,s,loc,z,t

SF,ALL,PRES,10000 ! APPLY PRESSURE LOAD

NSEL,ALL

FINISH

 

/SOLVE

OUTPR,,LAST

/OUT,SCRATCH

SOLVE

FINISH

/POST1

/OUT,

PRNSOL,S,COMP

PRNSOL,EPEL,COMP

PRNSOL,EF,COMP

PRNSOL,D,COMP

[Erik Kostson]

happy we could help.

See the video (post process) :

https://www.youtube.com/playlist?list=PLtt6-ZgUFmMKFfbOBhmCwG30KIVyvhDop

Also see the SET,LAST,LAST  POST1 command in the command reference

Erik