You can use surface-to-surface contact elements or the node-to-surface contact element, in combination with thermal-electric elements and solid coupled field elements to model electric current conduction. You can also use surface-to-surface contact elements, in combination with piezoelectric and electrostatic elements, to model electric charge across a contacting interface.
KEYOPT(1) provides degree of freedom options for modeling electric contact, as follows:
For combined structural/thermal/electric contact, set KEYOPT(1) = 3 to activate the structural, thermal, and electric DOFs.
For pure thermal/electric contact, set KEYOPT(1) = 4 to activate the thermal and electric DOFs.
For piezoelectric contact, set KEYOPT(1) = 5 to activate the structural and electric DOFs.
For electrostatic contact, set KEYOPT(1) = 6 to activate the electric DOF.
For structural/diffusion/thermal/electric contact, set KEYOPT(1) = 12 to activate the structural, concentration, thermal, and electric DOFs.
The electric contact features are:
Electric conduction between two contacting surfaces.
Heat generation due to electric dissipation.
Electric charge across the contacting interface.
To take into account the surface interaction for electric contact, you need to specify real constant ECC as the electric contact conductance per unit area in a current-based electric analysis or the electric contact capacitance per unit area in a charge-based electric analysis. Current-based analyses include electric conduction, thermo-electric, and piezoresistive analyses. Charge-based analyses include electrostatic and piezoelectric analyses.
You can use tabular input to define ECC as a function of contact pressure (pressure as a table), average temperature on contact detection point (temperature as a table), time, and other primary variables.
If the bonded contact or no-separation contact option is set, contact interaction can occur between two surfaces separated by a narrow gap.
The interaction between two contacting surfaces is defined by
where:
 = current density for the electric potential (VOLT)
degree of freedom (KEYOPT(1) = 3, 4, or
12), or the electric charge density (KEYOPT(1) = 5, or
6). |
 = electric contact conductance for the electric
potential (VOLT) degree of freedom (KEYOPT(1) = 3, 4, or 12), or the electric contact
capacitance per unit area for (KEYOPT(1) = 5, or 6). |
 and  = voltages at the contact points on the target and
contact surfaces. |
The ECC value is input through a real constant, which can be a function of
temperature (
), contact pressure (positive PRESSURE index values indicate
compression, negative PRESSURE index values indicate tension), geometric
penetration (positive GAP index values indicate penetration, negative GAP index
values indicate an open gap), time, and initial contact detection point location
(at the beginning of solution) by using tabular input (that is,
%tabname%). The user subroutine USERCNPROP is also
available for defining ECC (specify the table name %_CNPROP% as the real
constant value).
For the current conduction options, the electric contact conductance ECC has units of electric conductivity per unit area. For the electrostatic charge options, the electric contact capacitance ECC has units of capacitance per unit area.
To model surface interaction between two surfaces where a small gap exists, use KEYOPT(12) = 4 or 5 to define either the bonded contact or no-separation contact options (see Selecting Surface Interaction Models).
Note: For force-based node-to-surface contact, ECC has units of (electric conductivity * length) or the capacitance.
For electric current field analyses (KEYOPT(1) = 3 , 4, or 12), the heat generation due to electric current is given by
where
 = fraction of electric dissipated energy converted into
heat (Joule heating). This value defaults to 1 and can be input as a real
constant. For an input value of true 0, you must enter a very small value
(for example, 1 x 10-8). If you enter 0, the
program interprets this as an input of the default value. |
 = current density |
 and  = the voltages at the contact points on the contact and
target surfaces |
The amount of electric heat dissipation on contact and target surfaces is defined by
and
Where 
is the contact side and 
is the target side, and 
is the weight factor for the contact heat dissipation between the
contact and target surfaces (input as a real constant). FWGT is the same real
constant used for frictional heat generation. By default, 
. For an input of true 0, you must enter a very small value (for
example, 1 x 10-8). If you enter 0, the program
interprets this as an input of the default value.