GAPELECTR

User subroutine to define electrical conductance between surfaces in a coupled thermal-electrical or a coupled thermal-electrical-structural analysis.

User subroutine GAPELECTR:

assumes that the electrical current flowing between the interface surfaces is modeled as $J = σ_{g} (φ_{A} - φ_{B}),$ where J is the electrical current density flowing across the interface from point A (the secondary surface) to point B (the main surface), $φ_{A}$ and $φ_{B}$ are the electrical potential on opposite points of the surfaces, and $σ_{g}$ is the surface electrical conductance;
is used to define $σ_{g}$ , providing much greater flexibility than direct gap electrical conductance definition in specifying the dependencies of $σ_{g}$ (for example, it is not necessary to define the gap electrical conductance as a function of the average of the two surfaces' temperatures and/or field variables);
will be called at the secondary nodes of general contact (About General Contact in Abaqus/Standard) or contact pairs (About Contact Pairs in Abaqus/Standard) for which the gap electrical conductance is defined in a user subroutine; and
ignores any dependencies or data specified for the gap electrical conductance outside the user subroutine.

This page discusses:

User Subroutine Interface
Variables to Be Defined
Variables Passed in for Information

User Subroutine Interface

      SUBROUTINE GAPELECTR(SIGMA,D,TEMP,PREDEF,TIME,CINAME,
     1 SECNAME,MAINNAME,COORDS,NODE,NPRED,KSTEP,KINC)
C
      INCLUDE 'ABA_PARAM.INC'
C
      CHARACTER*80 CINAME,SECNAME,MAINNAME
C
      DIMENSION SIGMA(5),D(2),TEMP(2),PREDEF(2,*),TIME(2),
     1 COORDS(2,3)

      user coding to define SIGMA(1) -- SIGMA(5)

      RETURN
      END

Variables to Be Defined

SIGMA(1): Gap electrical conductance, $σ_{g}$ .
SIGMA(2): $\partial σ_{g} / \partial θ_{A}$ , derivative of the gap electrical conductance with respect to the temperature of point A. If the gap electrical conductance is not a function of $θ_{A}$ , SIGMA(2) = 0.0.
SIGMA(3): $\partial σ_{g} / \partial θ_{B}$ , derivative of the gap electrical conductance with respect to the temperature of point B. If the gap electrical conductance is not a function of $θ_{B}$ , SIGMA(3) = 0.0.
SIGMA(4): $\partial σ_{g} / \partial d$ , derivative of the gap electrical conductance with respect to the clearance between the bodies. If the gap electrical conductance is not a function of gap clearance, SIGMA(4)= 0.0. This variable needs to be defined only for a fully coupled thermal-electrical-structural analysis.
SIGMA(5): $\partial σ_{g} / \partial p$ , derivative of the gap electrical conductance with respect to the pressure between the bodies. If the gap electrical conductance is not a function of the pressure, SIGMA(5)= 0.0. This variable needs to be defined only for a fully coupled thermal-electrical-structural analysis.

Variables Passed in for Information

D(1): Separation between the interface surfaces, d.
D(2): Pressure transmitted across the surfaces, p.
TEMP(2): Current temperature at points A and B.
PREDEF(2,NPRED): An array containing pairs of values of all the user-specified field variables at the end of the current increment at points A and B (initial values at the beginning of the analysis and current values during the analysis).
TIME(1): Value of step time at the end of the increment.
TIME(2): Value of total time at the end of the increment.
CINAME: User-specified surface interaction name, left justified.
SECNAME: Secondary surface name.
MAINNAME: Main surface name.
COORDS: An array containing the current coordinates of points A and B. COORDS(1,K1) are the coordinates at point A, and COORDS(2,K1) are the coordinates at point B.
NODE: Secondary node number (point A).
NPRED: Number of predefined field variables.
KSTEP: Step number.
KINC: Increment number.