USDFLD

This problem contains basic test cases for one or more Abaqus elements and features.

The following topics are discussed:

Elements tested
Features tested
Problem description
Results and discussion
Input files
Figures

ProductsAbaqus/Standard

Elements tested

B21

CPE4

DC1D2

DC2D4

DS4

S4R

Features tested

User subroutine to redefine field variables at a material point.

Problem description

This set of tests verifies that field variable values are properly transferred to a structure when the values are redefined at run time. In every instance an Abaqus material model with dependency on a solution variable (such as temperature or equivalent plastic strain) is implemented with field-variable dependence. The appropriate field values are computed at run-time based on solution values from the previous increment. Every user-defined field variable model is checked against the equivalent Abaqus material model.

The hypoelastic material model is chosen as the basis for nonlinear elastic behavior at small strains for both static and dynamic analyses. Since Abaqus does not provide dependence of the hypoelastic tangent modulus on field variables, it was implemented using an elastic material with the equivalent secant modulus.

Results and discussion

A very close match is obtained between the user field variable approach and the corresponding Abaqus model. Figure 1 shows how the hypoelastic models compare in a static analysis. Matches of a similar nature can be obtained for the other files by using the time-history plotting capability available in the Visualization module of Abaqus/CAE.

Since the field variable approach uses values from the previous increment, the solution should improve as the time increment decreases. This trend was observed throughout.

Input files

udfcd1hs.inp: Steady-state heat transfer analysis, DC1D2 elements.
udfcd1hs.f: User subroutine USDFLD used in udfcd1hs.inp.
udfcd1ht.inp: Transient heat transfer analysis, DC1D2 elements.
udfcd1ht.f: User subroutine USDFLD used in udfcd1ht.inp.
udfcd2hs.inp: Steady-state heat transfer analysis, DC2D4 elements.
udfcd2hs.f: User subroutine USDFLD used in udfcd2hs.inp.
udfcd2ht.inp: Transient heat transfer analysis, DC2D4 elements.
udfcd2ht.f: User subroutine USDFLD used in udfcd2ht.inp.
udfcdshs.inp: Steady-state heat transfer analysis, DS4 elements.
udfcdshs.f: User subroutine USDFLD used in udfcdshs.inp.
udfcdsht.inp: Transient heat transfer analysis, DS4 elements.
udfcdsht.f: User subroutine USDFLD used in udfcdsht.inp.
udfebxdx.inp: Dynamic analysis, elastic, B21 elements.
udfebxdx.f: User subroutine USDFLD used in udfebxdx.inp.
udfebxsx.inp: Static analysis, elastic, B21 elements.
udfebxsx.f: User subroutine USDFLD used in udfebxsx.inp.
udfecxdx.inp: Dynamic analysis, elastic, CPE4 elements.
udfecxdx.f: User subroutine USDFLD used in udfecxdx.inp.
udfecxsx.inp: Static analysis, elastic, CPE4 elements.
udfecxsx.f: User subroutine USDFLD used in udfecxsx.inp.
udfesxdx.inp: Dynamic analysis, elastic, S4R elements.
udfesxdx.f: User subroutine USDFLD used in udfesxdx.inp.
udfesxsx.inp: Static analysis, elastic, S4/S4R elements.
udfesxsx.f: User subroutine USDFLD used in udfesxsx.inp.
udfpbxsf.inp: Static analysis followed by frequency analysis, elastic-plastic, B21 elements.
udfpbxsf.f: User subroutine USDFLD used in udfpbxsf.inp .
udfpcxsf.inp: Static analysis followed by frequency analysis, elastic-plastic, CPE4 elements.
udfpcxsf.f: User subroutine USDFLD used in udfpcxsf.inp.
udfpsxsf.inp: Static analysis followed by frequency analysis, elastic-plastic, S4/S4R elements.
udfpsxsf.f: User subroutine USDFLD used in udfpsxsf.inp.

Figures

Figure 1. Hypoelastic model comparison.