Electrical Analysis
An electrical analysis involves calculation of electric potential in structures subject to electrical loads.
 $${K}_{C}$$
 Electrical conduction matrix
 $$\phi $$
 Electric potential
 $$f$$
 Electric current
This is the equilibrium equation of electric currents and is solved for the unknown electric potential.
Electrical Analysis in OptiStruct
 SteadyState Electrical Conduction (SSEC)
 The loading (current or enforced voltage) is time independent.
 Multi Steady Electrical Conduction (MSEC)
 The loading (current or enforced voltage) is time dependent.
Coupled Electrical Analysis
Electrical analysis can be coupled with heat transfer analysis.
 SteadyState (linear/nonlinear) Heat Transfer analysis can only be coupled with SSEC.
 Transient (linear/nonlinear) Heat Transfer analysis can only be coupled
with MSEC.Note: Transient (linear/nonlinear) Heat Transfer analysis can still call an SSEC subcase via a DLOAD (that refers to a TLOAD, referencing a SSEC subcase). This is not a coupling and the solution from SSEC is used as a loading, like QVOL, in this case.
For an example use case, if the electrical load is constant and the electrical material is temperature independent, this method can greatly reduce computational time. Without this method, the solution must be computed at each timestep.
1Way Coupling
 Example 1: SteadyState Heat Transfer Analysis Calls SSEC as Loading

Subcase 101 ANALYSIS ELEC SPC = 20 LOAD = 22 Subcase 102 ANALYSIS HEAT SPC = 21 JOULE = 101 LOAD = 25
 Example 2: SSEC Uses SteadyState Heat Transfer Analysis to Update Material

SUBCASE 101 ANALYSIS ELEC SPC = 20 LOAD = 22 TEMP(MAT) = 102 SUBCASE 102 ANALYSIS HEAT SPC = 21 LOAD = 25
2Way Coupling
 SSEC Uses SteadyState Heat Transfer to Update Material
 Joule heating from SSEC is applied to steadystate heat transfer analysis.
 MSEC Uses Transient Heat Transfer Analysis to Update Material
 Joule heating from MSEC is applied to transient heat transfer analysis.
Examples for 1way and 2way coupling can be extended to nonlinear steadystate heat transfer subcases.
The TPID and TCID fields on PCONTEC entry are available to define tables for contact pressuredependent and contactclearance dependent resistance per unit area. The table lookup values are multiplied by the actual contact area to calculate the resistance.
Input
A summary of the relevant input file entries in an electrical analysis.
Entry  Purpose 

SPC, SPCD  Potential 
CURRENT  Nodal current 
CDENST4  Current density 
MAT1EC  Isotropic electrical material 
MAT2EC  Anisotropic electrical material 
MATT1EC, MATT2EC  Temperature dependent material 
PGAPEC  Electrical resistance properties for gap elements 
PCONTEC  Contact Electric Resistance Coefficient (CERC) for CONTACT element 
The TLOAD entry supports Joule loss density excitation (TYPE = J, JO, JOU, or JOUL). EXCITEID refers to the ID of a steadystate electrical subcase from which the Joule loss density can be applied to a transient heat transfer subcase.
Analogy
The following table summarizes the analogy of some electrical analysis entries with the existing thermal/structural analysis.
Type  Electrical Analysis  Thermal Analysis  Structural Analysis 

Result output  Electrical potential  Temperature  Displacement 
Electrical field  Temperature Gradient  Strain  
Loads and boundary conditions  CURRENT  FORCE  
CDENST4  QBDY1  PLOAD4  
SPC (Electrical potential)  SPC (Temperature)  SPC (Displacement)  
SPCD (Electrical potential)  SPCD (Temperature)  SPCD (Displacement)  
Material  MAT1EC  MAT4  MAT1 
MAT2EC  MAT5  MAT9  
MATT1EC  MATT4  MATT1  
MATT2EC  MATT5  MATT9 
Problem Setup
Example of an electrical analysis setup.
$ *************************************************************
$ EXAMPLE TO DEMONSTRATE AN ELECTRICAL ANALYSIS SETUP
$ *************************************************************
OLOAD = 11
VOLTAGE = 11
GPCURRENT = 11
ELECMAT = 22
ELECFIELD = 22
HEAT = 22
CURRDEN = 22
SUBCASE 1
LABEL HEAT
ANALYSIS HEAT
IC = 1
JOULE = 2
TSTEP = 9
DLOAD = 28
SPC = 12
NLPARM = 6
SUBCASE 2
LABEL ELEC
ANALYSIS ELEC
DLOAD = 3
SPC = 10
TEMP(MAT) = 1.
BEGIN BULK
...
Electrical Optimization
Optimization is supported for Electrical Analysis. Topology, Shape, Freeshape, Size, and Freesize optimization design variables are supported. The following responses are currently supported:
 The Nodal Electric Potential response is activated by setting the RTYPE field to ELPOT on the DRESP1 Bulk Data Entry. The GRID ID can be defined on the ATTi field.
 The Global Electric Compliance response is activated by setting the RTYPE field to ELCOMP on the DRESP1 Bulk Data Entry.
Example
A visual example of modeling Joule heating in a Busbar system.
Busbars are commonly used in many applications to provide power to various electronic boxes.
The model consists is an electrical system with five circuits. The circuits are separated from each other using a thin dielectric layer.
An initial temperature of 20 degrees Celsius is applied to all the bodies.
Output
Supported output requests for electrical analysis.
Currently, results are only available in .h3d format in a separate *_elecht.h3d file.
Result  Purpose  Details 

VOLTAGE  Voltage  Available by default 
HEAT  Joule loss density  Available by default 
CURRDEN  Current density  Available by default 
ELECFIELD  Electric field  
ELECMAT  Conductivity and resistivity  
GPCURRENT  Grid Point current  
OLOAD  Applied nodal current 
A current balance summary table is available in the .out file for steadystate electrical conduction analysis. This is similar to the SPCFORCE output table and consists of total applied current and SPC current.
This table is currently unavailable for MSEC analysis.