Help, How to apply Electrical Charge (Dz) boundary conditions?

[Lucy1995]

Dear friends,

I am using ANSYS 7.0 to simulate one static electro-elastic problem. I want to apply electrical displacement (Dz) boundary conditions on the model. However, I can not find the command by using GUI. Also, when I tried to use the command

F, 1, CHRG, 1.0

ANSYS gave me an error with "No CHRG".

Does that mean my version of ANSYS does not have the capability for applying electrical displacement BC? If it does, how should I do?

Thanks a lot!

 

[Drej]

Dz is not a valid label for a displacement constraint - your details are unclear, if you expand your problem in more detail more help can be given. What type of elements are you using? What is the analysis type? etc. etc. etc.

 

[Lucy1995]

hello, Drej:

I am analyzing one axisymmetric piezoceramics. The following is the detailed information.

Product: ANSYS Mechanical U
Individual discipline: Structrual with h-Method
Element type: PLANE13
Material Model: piezoceramics
Analysis type: Static

For piezoelectric material, there is one voltage degree of freedom more than Ux, Uy and Uz. Correspondingly, besides the stress field (e.g. Sigmaxx,Sigmayy, Sigmazz, Sigmaxy etc.), there are three electric displacement (also called electric flux density) field, Dx, Dy and Dz.

The problem is:
I can apply voltage boundary condition, just like apply displacement boundary conditions. However, I can not find how to apply electric flux density boundary condition, just like apply traction boundary conditions.

Hope anyone can figure this out.

Thanks!

 

[Drej]

Lucy

I am personally not familiar with this type of analysis, but I checked out the details for plane13 and it makes no mention of "electric displacement/electric flux density field, Dx, Dy and Dz" as an input or boundary condition.

Element Name
PLANE13
Nodes
I, J, K, L
Degrees of Freedom
AZ if KEYOPT (1) = 0
TEMP if KEYOPT (1 ) = 2
UX,UY if KEYOPT (1) = 3
UX, UY, TEMP, AZ if KEYOPT (1) = 4
VOLT, AZ if KEYOPT (1) = 6
UX, UY, VOLT if KEYOPT (1) = 7
Real Constants
None
Material Properties
EX, EY, EZ, (PRXY, PRYZ, PRXZ or NUXY, NUYZ, NUXZ),
ALPX, ALPY, ALPZ, DENS, GXY, DAMP,
KXX, KYY, C, ENTH, MUZERO, MURX,
MURY, RSVZ, MGXX, MGYY, PERX, PERY,
plus BH, ANEL, and Piezoelectric data tables (see Data Tables - Implicit Analysis)
Surface Loads

Pressures --
face 1 (J-I), face 2 (K-J), face 3 (L-K), face 4 (I-L)
Convections --
face 1 (J-I), face 2 (K-J), face 3 (L-K), face 4 (I-L)
Heat Fluxes --
face 1 (J-I), face 2 (K-J), face 3 (L-K), face 4 (I-L)
Maxwell Force Flags --
face 1 (J-I), face 2 (K-J), face 3 (L-K), face 4 (I-L)

Body Loads

Temperatures --
T (I), T (J), T (K), T (L)
Heat Generations --
HG (I), HG (J), HG (K), HG (L)
Magnetic Virtual Displacements --
VD (I), VD (J), VD (K), VD (L)
Source Current Density --
spare, spare, JSZ (I), PHASE (I), spare, spare,
JSZ (J), PHASE (J), spare, spare, JSZ (K), PHASE (K),
spare, spare, JSZ (L), PHASE (L)

It mentions in "Table 13.1. PLANE13 Element Output Definitions" the "D: X, Y Electric flux density components (X,Y)", but hence this appears to be an output option only. Have you looked in the help file under plane13 to check this for yourself? Is your problem that there is no option to apply the electric flux density components within the GUI?

-- drej --

 

[ScottMf]

From what you've said it sounds like you are trying to apply a surface charge density (coulombs/m^2) to your elements. Reading through the help files it looks like you will have to use a plane223 to do this. Then you can use SF,nodes,CHGS,1.0 where nodes define the surfaces you want to apply the electric flux density to.

Good luck,
~Scott

 

[reno001]

Hello Lucy
You may find interesting things at the following email address.

http://dmt

http://www.epfl.ch/ims/micsys/ANSYS/tp/index.html

Renaud