PRORB
PRORB, WhrlNodKey
Prints the orbital motion characteristics of a rotating
structure
WhrlNodKeyFlag to print the whirl for each node:
1 (ON or YES)
—
Print the whirl for each node.
0 (OFF or NO)
—
No printout. This value is the default.
Notes
When a structure is rotating and the Coriolis or gyroscopic effect is taken into account (CORIOLIS), nodes lying on the rotation axis generally exhibit an elliptical orbital motion. The PRORB command prints out the orbit characteristics A, B, PSI, PHI, YMAX, ZMAX, and Whirl of each rotating node, where
| A is the semi-major axis. |
| B is the semi-minor axis. |
| PSI is the angle between local y axis and major axis. |
| PHI is the angle between initial position (t = 0) and major axis. |
| YMAX is the maximum displacement along local y axis. |
| ZMAX is the maximum displacement along local z axis. |
| Whirl is the direction of an orbital motion (BW for backward whirl and FW for forward whirl). |
Angles PSI and PHI are in degrees and within the range of -180 through +180.
To display the characteristics of the orbital path traversed by each node, issue the PLORB command.
The PRORB command is valid for line elements (such as BEAM188, BEAM189, PIPE288, and PIPE289). PRORB is not supported for beam elements with the warping degree of freedom activated.
Your model must also involve a rotational velocity (OMEGA or CMOMEGA) with Coriolis enabled (CORIOLIS).
Because orbit data is written in the database, a SET command must be issued after the PRORB command to ensure proper output for subsequent postprocessing commands.
The coordinate system for displaying nodal results must be global
Cartesian (RSYS,KCN = 0). PRORB
is not supported if nodes are rotated in a cylindrical coordinate system.