Product: Abaqus/Standard
User subroutine UTRSNETWORK:
can be used to define a time-temperature shift for a nonlinear viscoelastic network for models defined using the parallel rheological framework;
will be called for all material points of elements for which a user-defined shift function is specified to define the time-temperature correspondence as part of the viscoelastic material definition;
can use and update solution-dependent state variables; and
can be used in conjunction with user subroutine USDFLD to redefine any field variables before they are passed in.
subroutine utrsnetwork (
C Must be updated
* outputData,
C Can be updated
* statev,
C Information (Read only)
* nOutput,
* nstatv,
* networkid,
* coords,
* temp,
* dtemp,
* nfield,
* predef,
* dpred,
* nprops,
* props,
* i_array,
* niarray,
* r_array,
* nrarray,
* c_array,
* ncarray)
C
include 'aba_param.inc'
C
parameter( io_trs_shift_begin = 1,
* io_trs_shift_end = 2 )
C
parameter( i_trs_kstep = 1,
* i_trs_kinc = 2,
* i_trs_noel = 3,
* i_trs_npt = 4,
* i_trs_layer = 5,
* i_trs_kspt = 6 )
C
parameter( ir_trs_step_time = 1,
* ir_trs_total_time = 2,
* ir_trs_creep_time = 3,
* ir_trs_timeinc = 4 )
C
parameter( ic_trs_material_name = 1 )
C
dimension
* statev(nstatv),
* predef(nfield),
* dpred(nfield),
* props(nprops),
* coords(*),
* outputData(nOutput),
* i_array(niarray),
* r_array(nrarray)
character*80 c_array(ncarray)
C
user coding to define outputData(io_trs_shift_begin)
and outputData(io_trs_shift_end)
return
endoutputData(io_trs_shift_begin)
The shift function at the beginning of the increment.
outputData(io_trs_shift_end)
The shift function at the end of the increment.
statev
An array containing the user-defined solution-dependent state variables at this point.
nOutput
Size of array outputData. Currently equal to 2.
nstatv
Number of solution-dependent state variables associated with this material.
networkid
Network identification number, which identifies the network for which creep is defined.
coords
An array containing the current coordinates at this point.
temp
Temperature at the end of the increment.
dtemp
Increment of temperature.
nfield
Number of field variables.
predef
An array of interpolated values of predefined field variables at this point at the end of the increment, based on the values read in at the nodes and, optionally, redefined in user subroutine USDFLD.
dpred
An array of increments of predefined field variables.
nprops
User-specified number of user-defined material properties.
props
An array of user-specified property values.
i_array(i_trs_kstep)
Step number.
i_array(i_trs_kinc)
Increment number.
i_array(i_trs_noel)
Element number.
i_array(i_trs_npt)
Integration point.
i_array(i_trs_layer)
Layer number (for layered solids).
i_array(i_trs_kspt)
Section point number within the current layer.
niarray
Size of array i_array. Currently equal to 6.
r_array(ir_trs_step_time)
Value of step time at the end of the increment.
r_array(ir_trs_total_time)
Value of total time at the end of the increment.
r_array(ir_trs_creep_time)
Value of creep time at the end of the increment.
r_array(ir_trs_timeinc)
Time increment.
nrarray
Size of array r_array. Currently equal to 4.
c_array(ic_trs_material_name)
User-specified material name, left justified. Some internal material models are given names starting with the “ABQ_” character string. To avoid conflict, you should not use “ABQ_” as the leading string for the material name.
ncarray
Size of array c_array. Currently equal to 1.
As an example of the coding of user subroutine UTRSNETWORK, consider the William-Landel-Ferry model to define the shift function. In this case the shift function is expressed as (see “Thermo-rheologically simple temperature effects” in “Time domain viscoelasticity,” Section 22.7.1 of the Abaqus Analysis User's Guide)
is the temperature,
is the reference temperature, and
and 
are constants.
The user subroutine would be coded as follows:
subroutine utrsnetwork (
C Must be updated
* outputData,
C Can be updated
* statev,
C Information (Read only)
* nOutput,
* nstatv,
* networkid,
* coords,
* temp,
* dtemp,
* nfield,
* predef,
* dpred,
* nprops,
* props,
* i_array,
* niarray,
* r_array,
* nrarray,
* c_array,
* ncarray)
C
include 'aba_param.inc'
C
parameter( io_trs_shift_begin = 1,
* io_trs_shift_end = 2 )
C
parameter( i_trs_kstep = 1,
* i_trs_kinc = 2,
* i_trs_noel = 3,
* i_trs_npt = 4,
* i_trs_layer = 5,
* i_trs_kspt = 6 )
C
parameter( ir_trs_step_time = 1,
* ir_trs_total_time = 2,
* ir_trs_creep_time = 3,
* ir_trs_timeinc = 4 )
C
parameter( ic_trs_material_name = 1 )
C
C
parameter( zero=0.0d0, one=1.0d0, dln10=2.30258509299d0)
C
dimension
* statev(nstatv),
* predef(nfield),
* dpred(nfield),
* props(nprops),
* coords(*),
* outputData(nOutput),
* i_array(niarray),
* r_array(nrarray)
character*80 c_array(ncarray)
C
outputData(io_trs_shift_begin) = zero
outputData(io_trs_shift_end) = zero
temp0 = temp-dtemp
C
C WLF
C
theta0 = props(1)
C1 = props(2)
C2 = props(3)
outputData(io_trs_shift_begin) =
& exp(-dln10*C1*(temp0-theta0)/(C2+(temp0-theta0)))
outputData(io_trs_shift_end) =
& exp(-dln10*C1*(temp-theta0)/(C2+(temp-theta0)))
C
return
end