Mechanical APDL Basic Analysis Guide - Ansys

the shell, and 270° to 360° for the lower half. The surface to be loaded crosses the singularity, a violation of
Guideline 1:
CSCIR,11,1 ! Change singularity to 0°
SFGRAD,PRES,11,Y,270,1 ! Slope the pressure in the theta direction
! of C.S. 11. Specified pressure in effect
! at 270°, tapering at 1 unit per degree
SF,ALL,PRES,400 ! Pressure at all selected nodes:
! 400 at 270°, 490 at 360°, 220 at +90°
! and 130 at 0°
Again the program will use a load value of 400 at 270° and a slope of 1 unit per degree to calculate the
applied load values of 400 at 270°, 490 at 360°, 220 at 90°, and 130 at 0°. Violating Guideline 1 will cause a
singularity in the tapered load itself, as shown on the right in Figure 2.11 (p. 38). Due to node discretization,
the actual load applied will not change as abruptly at the singularity as it is shown in the figure. Instead,
the node at 0° will have the load value of, in the case shown, 130, while the next node clockwise (say, at
358°) will have a value of 488.
Note
The SFGRAD specification stays active for all subsequent load application commands. To remove
the specification, simply issue SFGRAD without any arguments. Also, if an SFGRAD specification
is active when a load step file is read, the program erases the specification before reading the
file.
Large deflection effects can change the node locations significantly. The SFGRAD slope and load value calculations,
which are based on node locations, are not updated to account for these changes. If you need
this capability, use SURF153 with face 3 loading or SURF154 with face 4 loading.
2.5.7.4. Repeating a Surface Load
By default, if you repeat a surface load at the same surface, the new specification replaces the previous one.
You can change this default to add (for accumulation) or ignore using one of the following:
Command(s): SFCUM
GUI: Main Menu> Preprocessor> Loads> Define Loads> Settings> Replace vs. Add> Surface Loads
Main Menu> Solution> Define Loads> Settings> Replace vs. Add> Surface Loads
Any surface load you set stays set until you issue another SFCUM command. To reset the default setting
(replacement), simply issue SFCUM without any arguments. The SFSCALE command allows you to scale
existing surface load values. Both SFCUM and SFSCALE act only on the selected set of elements. The Lab
field allows you to choose the surface load label.
2.5.7.5. Transferring Surface Loads
To transfer surface loads that have been applied to the solid model to the corresponding finite element
model, use one of the following:
Command(s): SFTRAN
GUI: Main Menu> Preprocessor> Loads> Define Loads> Operate> Transfer to FE> Surface Loads
Main Menu> Solution> Define Loads> Operate> Transfer to FE> Surface Loads
To transfer all solid model boundary conditions, use the SBCTRAN command. (See DOF Constraints (p. 27)
for a description of DOF constraints.)
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2.5.7. Surface Loads
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