Figure 2.10: Tapered Load on a Cylindrical Shell
You might think to specify 270°, rather than -90°, for SLZER, as follows:
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 -90°, 490 at 0°, 580 at +90°As shown on the left in Figure 2.11:Violation of Guideline 2 (left) and Guideline 1 (right) (p. 38), however,
specifying 270° results in a tapered load much different than the one intended. This behavior occurs
because the singularity is still located at 180° (the θ coordinates still range from -90° to +90°), but SLZER
is not between -180° and +180°. As a result, the program uses a load value of 400 at 270°, and a slope
of 1 unit per degree to calculate the applied load values of 220 at +90°, 130 at 0°, and 40 at -90°. Avoid
this behavior by following the second guideline, that is, specifying SLZER to be a value between ±180°
when the singularity is at 180°, and between 0° and 360° when the singularity is at 0°.
Figure 2.11: Violation of Guideline 2 (left) and Guideline 1 (right)
40040310 130
220+90°+ 180 °
0 °- 90 °
- 270 °
2200 °+90°+ 180 °+ 270 °+ 360 °130
310400490y xy(^11)
s ingularity
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