Available user subroutines

User subroutines allow advanced users to customize a wide variety of Abaqus capabilities. Information on writing user subroutines and detailed descriptions of each subroutine appear online in the Abaqus User Subroutines Guide. A listing and explanations of associated utility routines also appear in that guide.

The following topics are discussed:

Available user subroutines for Abaqus/Standard
Available user subroutines for Abaqus/Explicit

Available user subroutines for Abaqus/Standard

The available user subroutines for Abaqus/Standard are as follows:

CREEP: Define time-dependent, viscoplastic behavior (creep and swelling).
DFLOW: Define nonuniform pore fluid velocity in a consolidation analysis.
DFLUX: Define nonuniform distributed flux in a heat transfer or mass diffusion analysis.
DISP: Specify prescribed boundary conditions.
DLOAD: Specify nonuniform distributed loads.
FILM: Define nonuniform film coefficient and associated sink temperatures for heat transfer analysis.
FLOW: Define nonuniform seepage coefficient and associated sink pore pressure for consolidation analysis.
FRIC: Define frictional behavior for contact surfaces.
FRIC_COEF: Define frictional coefficient for contact surfaces.
GAPCON: Define conductance between contact surfaces or nodes in a fully coupled temperature-displacement analysis, a fully coupled thermal-electrical-structural analysis, or a pure heat transfer analysis.
GAPELECTR: Define electrical conductance between surfaces in a coupled thermal-electric analysis or a fully coupled thermal-electrical-structural analysis.
HARDINI: Define initial equivalent plastic strain and initial backstress tensor.
HETVAL: Provide internal heat generation in heat transfer analysis.
MPC: Define multi-point constraints.
ORIENT: Provide an orientation for defining local material directions or local directions for kinematic coupling constraints or local rigid body directions for inertia relief.
RSURFU: Define a rigid surface.
SDVINI: Define initial solution-dependent state variable fields.
SIGINI: Define an initial stress field.
UAMP: Specify amplitudes.
UANISOHYPER_INV: Define anisotropic hyperelastic material behavior using the invariant formulation.
UANISOHYPER_STRAIN: Define anisotropic hyperelastic material behavior based on Green strain.
UCORR: Define cross-correlation properties for random response loading.
UCREEPNETWORK: Define time-dependent behavior (creep) for models defined within the parallel rheological framework.
UDECURRENT: Define nonuniform volume current density in an eddy current or magnetostatic analysis.
UDEMPOTENTIAL: Define nonuniform magnetic vector potential on a surface in an eddy current or magnetostatic analysis.
UDMGINI: Define the damage initiation criterion.
UDSECURRENT: Define nonuniform surface current density in an eddy current or magnetostatic analysis.
UEL: Define an element.
UELMAT: Define an element with access to Abaqus materials.
UEPACTIVATIONVOL: Specify material volume fraction added during element activation.
UEXPAN: Define incremental thermal strains.
UEXTERNALDB: Manage user-defined external databases and calculate model-independent history information.
UFIELD: Specify predefined field variables.
UFLUID: Define fluid density and fluid compliance for hydrostatic fluid elements.
UFLUIDCONNECTORLOSS: Define the connector loss for fluid pipe connector elements.
UFLUIDCONNECTORVALVE: Define the valve opening to control flow in fluid pipe connector elements.
UFLUIDLEAKOFF: Define the fluid leak-off coefficients for pore pressure cohesive elements.
UFLUIDPIPEFRICTION: Define the friction coefficient for fluid pipe elements.
UGENS: Define the mechanical behavior of a shell section.
UHARD: Define the yield surface size and hardening parameters for isotropic plasticity or combined hardening models.
UHYPEL: Define a hypoelastic stress-strain relation.
UHYPER: Define a hyperelastic material.
UINTER: Define surface interaction behavior for contact surfaces.
UMASFL: Specify prescribed mass flow rate conditions for a convection/diffusion heat transfer analysis.
UMAT: Define a material's mechanical behavior.
UMATHT: Define a material's thermal behavior.
UMDFLUX: Specify moving or stationary nonuniform heat flux in a heat transfer analysis.
UMESHMOTION: Specify mesh motion constraints during adaptive meshing.
UMOTION: Specify motions during cavity radiation heat transfer analysis or steady-state transport analysis.
UMULLINS: Define damage variable for the Mullins effect material model.
UPOREP: Define initial fluid pore pressure.
UPRESS: Specify prescribed equivalent pressure stress conditions.
UPSD: Define the frequency dependence for random response loading.
URDFIL: Read the results file.
USDFLD: Redefine field variables at a material point.
USUPERELASHARDMOD: Modify the material constants of the superelasticity model as a function of the plastic strain.
UTEMP: Specify prescribed temperatures.
UTRACLOAD: Specify nonuniform traction loads.
UTRS: Define a reduced time shift function for a viscoelastic material.
UTRSNETWORK: Define a reduced time shift function for models defined within the parallel rheological framework.
UVARM: Generate element output.
UWAVE: Define wave kinematics for an Abaqus/Aqua analysis.
UXFEMNONLOCALWEIGHT: Define the weight function used to compute the average stress/strain to determine the crack propagation direction.
VOIDRI: Define initial void ratios.

Available user subroutines for Abaqus/Explicit

The available user subroutines for Abaqus/Explicit are as follows:

VDFLUX: User subroutine to specify nonuniform distributed fluxes in an explicit dynamic coupled temperature-displacement analysis.
VDISP: Specify prescribed boundary conditions.
VDLOAD: Specify nonuniform distributed loads.
VEXTERNALDB: Control analyses to exchange data among Abaqus user subroutines and external programs or files.
VFABRIC: Define fabric material behavior.
VFRIC: Define contact frictional behavior between surfaces defined with the contact pair algorithm.
VFRIC_COEF: Define contact frictional coefficient between surfaces defined with the general contact algorithm.
VFRICTION: Define contact frictional behavior between surfaces defined with the general contact algorithm.
VUAMP: Specify amplitudes.
VUANISOHYPER_INV: Define anisotropic hyperelastic material behavior using the invariant formulation.
VUANISOHYPER_STRAIN: Define anisotropic hyperelastic material behavior based on Green strain.
VUCHARLENGTH: Define characteristic element length at a material point.
VUCREEPNETWORK: Define time-dependent behavior (creep) for models defined within the parallel rheological framework.
VUEL: Define an element.
VUEOS: Define equation of a state material model.
VUEXPAN: Define thermal strain increments.
VUFIELD: Specify predefined field variables.
VUFLUIDEXCH: Define mass/heat energy flow rates for fluid exchange.
VUFLUIDEXCHEFFAREA: Define effective area for fluid exchange.
VUHARD: Define the yield surface size and hardening parameters for isotropic plasticity or combined hardening models.
VUINTER: Define the contact interaction between surfaces defined with the contact pair algorithm.
VUINTERACTION: Define the contact interaction between surfaces defined with the general contact algorithm.
VUMAT: Define material behavior.
VUMULLINS: Define damage variable for the Mullins effect material model.
VUSDFLD: Redefine field variables at a material point.
VUSUPERELASHARDMOD: Modify the material constants of the superelasticity model as a function of the plastic strain.
VUTRS: Define a reduced time shift function for a viscoelastic material.
VUVISCOSITY: Define the shear viscosity for equation of state models.
VWAVE: Define wave kinematics for an Abaqus/Aqua analysis.