If you specify a discrete
field for a prescribed condition,
Abaqus/CAE
evaluates the discrete field when the input file is written.
If an element or node is found in both the region selected for the
prescribed condition and the discrete field,
Abaqus/CAE
multiplies the magnitude of the prescribed condition by the value at each
element or node to determine the final values that are submitted to the
analysis. A material assignment predefined field is the only exception; this
prescribed condition has no magnitude.
If an element or node is found in the region selected for the prescribed
condition but not in the discrete field, the magnitude of the prescribed
condition is multiplied by the default value and submitted to the analysis.
Table 1
summarizes how the value written to the input file is determined for scalar
discrete fields.
Table 1. Evaluating scalar discrete fields.
Element or node in region selected
for prescribed condition?
Element or node in discrete field?
Value written to input file
Yes
Yes
Magnitude of prescribed condition × magnitude specified in
discrete field
Yes
No
Magnitude of prescribed condition × default value specified in
discrete field
No
Yes
Not written to input file
For prescribed conditions that have multiple degrees of freedom, such as
displacements, prescribed condition discrete fields are used; and evaluating
the discrete field becomes more complex. For prescribed conditions where you
can activate the individual degrees of freedom, only the active degrees of
freedom in the prescribed condition are considered; any degree of freedom that
is not active in the prescribed condition will be ignored. The magnitudes
specified for each degree of freedom in the prescribed condition are multiplied
by either the magnitude specified in the discrete field or the default value
for that degree of freedom in the discrete field.
For example, if you define a displacement boundary condition, as shown in
Figure 1,
for Node-set-1 (containing nodes
Part-2–1.10,
Part-2–1.20, and
Part-2–1.30) and a prescribed condition discrete
field, as shown in
Figure 2,
the values that are submitted to the input file are shown in
Table 2.
Table 2. Results for evaluating a prescribed condition discrete field.
Node ID
Degree of freedom
Value written to input file
Part-2-1.10
3 (U3)
30
Part-2-1.10
4 (UR1)
600
Part-2-1.20
3 (U3)
70
Part-2-1.20
4 (UR1)
600
Part-2-1.30
3 (U3)
70
Part-2-1.30
4 (UR1)
600
Part-2-1.40
3 (U3)
None
Degrees of freedom for boundary conditions and predefined fields that result
in a zero magnitude are written to the input file as such; however, degrees of
freedom for loads that result in zero magnitudes are not written to the input
file.
When creating discrete fields that will be used with assembly-level and
history objects, such as loads or interactions, you must specify the complete
name of the node or element numbers, as described in
Naming Conventions.