Specifying user-defined field variables directly in the input file

Features tested

Direct method to redefine a field variable at a material point by associating it with a scalar output variable.

Problem description

In the direct approach, the appropriate field values are set equal to values of a scalar output variable from the previous increment automatically at run time. The tests verify that field variable values are transferred properly to a structure when the values are redefined at run time in the above manner.

Results and discussion

The results obtained using the direct approach are compared with the corresponding results from an identical model that utilizes user subroutine USDFLD to redefine field variables during an increment.

Input files

Abaqus/Standard analyses

plastic_udfld_specified_s.inp: An elastic-plastic material that has a built-in dependency on a solution variable (the equivalent plastic strain) is implemented with field variable dependence. In addition, the elastic-plastic hardening behavior is enhanced to include different hardening in tension versus compression. The latter utilizes field variable dependence, with the field variable associated with the hydrostatic pressure.
plastic_udfld_user_s.inp: The same setup as plastic_udfld_specified_s.inp, except that the field variables are redefined by user subroutine USDFLD.
plastic_udfld_user_s.f: User subroutine USDFLD used in plastic_udfld_user_s.inp.
udfcd1ht_sp.inp: Transient heat transfer analysis, DC1D2 elements. This model uses the USER DEFINED FIELD, TYPE=SPECIFIED option.
udfpbxsf_sp.inp: Static analysis followed by frequency analysis, elastic-plastic, B21 elements. This model uses the USER DEFINED FIELD, TYPE=SPECIFIED option.
udfpsxsf_sp.inp: Static analysis followed by frequency analysis, elastic-plastic, S4/S4R elements. This model uses the USER DEFINED FIELD, TYPE=SPECIFIED option.

Abaqus/Explicit analyses

plastic_udfld_specified_x.inp: An elastic-plastic material that has a built-in dependency on a solution variable (the equivalent plastic strain) is implemented with field variable dependence. In addition, the elastic-plastic hardening behavior is enhanced to include different hardening in tension versus compression. The latter utilizes field variable dependence, with the field variable associated with the hydrostatic pressure.