FRIC_COEF

User subroutine to define the frictional coefficient for contact surfaces.

User subroutine FRIC_COEF:

can be used to define the isotropic frictional coefficient between contacting surfaces;
corresponds to the classical Coulomb friction model; and
can be used with the contact pair and general contact algorithms.

The following topics are discussed:

User subroutine interface
Variables to be defined
Variables passed in for information

User subroutine interface

      subroutine fric_coef (
C Write only - 
     *   fCoef, fCoefDeriv, 
C Read only - 
     *   nBlock, nProps, nTemp, nFields, 
     *   jFlags, rData, 
     *   surfInt, surfSlv, surfMst, 
     *   props, slipRate, pressure, 
     *   tempAvg, fieldAvg )
C
      include 'aba_param.inc'
C
      dimension fCoef(nBlock), 
     *   fCoefDeriv(nBlock,3),
     *   props(nProps),
     *   slipRate(nBlock),
     *   pressure(nBlock),
     *   tempAvg(nBlock), 
     *   fieldAvg(nBlock,nFields)
C
      parameter( iKStep   = 1,
     *           iKInc    = 2,
     *           nFlags   = 2 )
C
      parameter( iTimStep = 1,
     *           iTimGlb  = 2,
     *           iDTimCur = 3,
     *           nData    = 3 )
C
      dimension jFlags(nFlags), rData(nData)
C
      character*80 surfInt, surfSlv, surfMst 
C
      user coding to define fCoef
      return
      end

Variables to be defined

fCoef(nBlock): This array must be updated to the current values of the friction coefficient at the contact point.
fCoefDeriv(nBlock,3): This array must be updated to the derivatives of the friction coefficient with respect to slip rate, pressure, and temperature at the contact point.

Variables passed in for information

nBlock: Equal to 1.
nProps: User-specified number of property values associated with this friction model.
nTemp: 1 if the temperature is defined and 0 if the temperature is not defined.
nFields: Number of user-specified field variables.
jFlag(1): Step number.
jFlag(2): Increment number.
rData(1): Value of step time.
rData(2): Value of total time.
rData(3): Current increment in time from $t = t_{c u r r} - Δ t$ to $t = t_{c u r r}$ .
surfInt: User-specified surface interaction name, left justified.
surfSlv: Slave surface name, left justified.
surfMst: Master surface name, left justified.
props(nProps): User-specified vector of property values to define the frictional coefficient at the contact point.
slipRate(nBlock): This array contains the rate of tangential slip at the contact point for the current time increment.
pressure(nBlock): This array contains the pressure at the contact point projected at the end of the current time increment.
tempAvg(nBlock): Average current temperature between the master and slave surfaces at the contact point.
fieldAvg(nBlock,nFields): Average current value of all the user-specified field variables between the master and slave surfaces at the contact point.