Product: ABAQUS/Standard
User subroutine UMULLINS:
can be used to define the damage variable for the Mullins effect material model, including the use of the Mullins effect approach to model energy dissipation in elastomeric foams;
will be called at all material calculation points of elements for which the material definition contains a user-defined Mullins effect; and
should be used when you do not want to use the form of the damage variable, 
, that is used by ABAQUS/Standard.
SUBROUTINE UMULLINS(NUMPROPS,PROPS,UMAXNEW,UMAXOLD,SEDDEV,
1 ETA,DETADW,DMGDISSOLD,DMGDISSNEW,SENERNEW,NUMSTATEV,STATEV,
2 TEMP,DTEMP,NUMFIELDV,FIELDV,FIELDVINC,CMNAME,LINPER)
C
INCLUDE 'ABA_PARAM.INC'
C
CHARACTER*80 CMNAME
DIMENSION PROPS(*),STATEV(*),FIELDV(*),FIELDVINC(*)
user coding to define ETA, DETADW,
and, optionally, DMGDISSNEW, SENERNEW, STATEV
RETURN
ENDETA
The damage variable, .
DETADW
The derivative of the damage variable with respect to the elastic strain energy density of the undamaged material, 
. This quantity is needed for the Jacobian of the overall system of equations and needs to be defined accurately to ensure good convergence characteristics.
DMGDISSNEW
The energy dissipation density at the end of the increment. This quantity can be defined either in total form or in an incremental manner using the old value of the damage dissipation DMGDISSOLD and the increment in damage dissipation. This quantity is used for output purposes only.
SENERNEW
The recoverable strain energy density at the end of the increment. This quantity is used for output purposes only.
STATEV
Array containing the user-defined solution-dependent state variables at this point. These are supplied as values at the start of the increment or as values updated by other user subroutines (see “User subroutines: overview,” Section 25.1.1) and must be returned as values at the end of the increment.
UMAXNEW
The value, at the end of the increment, of the maximum primary strain energy density over its entire deformation history.
UMAXOLD
The value, at the beginning of the increment, of the maximum primary strain energy density over its entire deformation history.
SEDDEV
The value, at the end of the increment, of the deviatoric primary strain energy density when the primary material behavior is hyperelastic. The value, at the end of the increment, of the total primary strain energy density when the primary material behavior is hyperfoam.
DMGDISSOLD
The value of energy dissipated at the beginning of the increment.
CMNAME
User-specified material name, left justified.
NUMSTATEV
Number of solution-dependent state variables associated with this material (defined as described in “Allocating space” in “User subroutines: overview,” Section 25.1.1).
NUMPROPS
Number of material properties entered for this user-defined hyperelastic material.
PROPS
Array of material properties entered for this user-defined hyperelastic material.
TEMP
Temperature at the start of the increment.
DTEMP
Increment of temperature.
NUMFIELDV
Number of field variables.
FIELDV
Array of interpolated values of predefined field variables at this material point at the beginning of the increment based on the values read in at the nodes (initial values at the beginning of the analysis and current values during the analysis).
FIELDVINC
Array of increments of predefined field variables at this material point for this increment; this includes any values updated by user subroutine USDFLD.
LINPER
Linear perturbation flag. LINPER=1 if the step is a linear perturbation step. LINPER=0 if the step is a general step.