Learning Forum

[jeremysawzy03]

Hello,
ive been trying to model a an aluminium plates attached to piezoelectric shunted circuit (https://doi.org/10.1016/j.ymssp.2018.04.041) using coupled field harmonic-mechanical in ansys. I model piezoelectric patches to be solid226 elements with electrical DOF using command APDL sniphets( ET, matid, solid226, 1001). In addition ive also added fixed support on all sides of the aluminium plate, grounded the inner sides of the piezoelectric patches, added pressure of 1 Pa to one side of the plate. 
In order to model the shunted circuit, ive additionally added a command APDL, basically coupling top surface and bot surface of the piezoelectric patches' electrical DOF to a terminal node; adding resistor in the circuit element and finally connecting circuit across top and bottom terminal node, APDL:

/PREP7           ! Enter preprocessor

!Creating top/bot surfaces
ALLSEL, ALL             ! clear selection filters
NSEL, S, LOC, Z, 0.00125  !Select top surface
CM, TOP_SURF_NODES, NODE     ! Create component of top surface nodes

ALLSEL, ALL             ! clear selection filters
NSEL, S, LOC, Z, -0.00125      ! Select bot surface
CM, BOT_SURF_NODES, NODE     ! Create component of bottom surface nodes

!Creating 2 new nodes for external terminal
N, 70000, 0.25, 0.25, 0.00125 ! top terminal node
N, 70001, 0.25, 0.25, -0.00125 ! bot terminal node

ETLIST

!Coupling the entire surface to nodes
ALLSEL, ALL             ! clear selection filters
SELTOL, 1e-8          !selecting tolerance

!Coupling top surface
CMSEL, S, TOP_SURF_NODES
!NSEL, S, NODE          ! Select top surface nodes
NSEL, A, NODE,, 70000, 70000   ! Add terminal node last
CP, 100, VOLT, ALL

!Coupling bot surface
CMSEL, S, BOT_SURF_NODES
!NSEL, S, NODE
NSEL, A, NODE,, 70001, 70001
CP, 101, VOLT, ALL

!CP, 101, VOLT, 16001, ALL   !All bot nodes share VOLT with 16001
ALLSEL, ALL

ALLSEL, ALL             ! clear selection filters
! Connect circuit element
ET, 100, CIRCU94
R, 2, 1000      !1kOhm
TYPE, 100
REAL, 2
E, 70000, 70001         ! Connect circuit across top and bottom

! No /STATUS or /SOLU here - Workbench handles that
FINISH
------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------

Im getting a warning like these: 

 *GET  ANSINTER_  FROM  ACTI  ITEM=INT        VALUE=  0.00000000    

 *IF  ANSINTER_  ( =   0.00000     )  NE  
      0  ( =   0.00000     )  THEN    

 *ENDIF

 *** WARNING ***                         CP =       0.766   TIME= 10:49:58
 SOLVE is not a recognized BEGIN command, abbreviation, or macro.  This  
 command will be ignored.                                                
 *************** Write FE CONNECTORS *********

 *** WARNING ***                         CP =       0.766   TIME= 10:49:58
 CEWRITE is not a recognized BEGIN command, abbreviation, or macro.      
 This command will be ignored.                                           

 PRINTOUT RESUMED BY /GOP

 *GET  _WALLASOL  FROM  ACTI  ITEM=TIME WALL  VALUE=  10.8327778    
---------------------------------------------------------------------------------------------------------------------------------------------------
i dont know why solve is ignored in this case, should i have approached this problem the other way? 

[mrife]

Hi jeremysawzy03

I take it the commands object listing is the CO that is attached to the coupled field harmonic environment (and not either of the two on the geometries).  The commands are inserted to the input file AFTER the /solu command that Mechanical writes.  So you need to reenter /solu at the end of the commands object.  I.E. here:

! No /STATUS or /SOLU here - Workbench handles that
FINISH

Instead use:

FINISH

/solu

mike