4.1.20 USDFLD

4.1.20 `USDFLD`

Product: ABAQUS/Standard

Elements tested

B21 CPE4 DC1D2 DC2D4 DS4 S4 S4R

Feature 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 by using *ELASTIC 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 4.1.20–1 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.