omega#

Inertia.omega(omegx='', omegy='', omegz='', **kwargs)#

Specifies the rotational velocity of the structure.

Mechanical APDL Command: OMEGA

Parameters:
omegxstr

Rotational velocity of the structure about the global Cartesian X, Y, and Z axes.

omegystr

Rotational velocity of the structure about the global Cartesian X, Y, and Z axes.

omegzstr

Rotational velocity of the structure about the global Cartesian X, Y, and Z axes.

Notes

This command specifies the rotational velocity of the structure about each of the global Cartesian axes (right-hand rule). Rotational velocities may be defined in these analysis types:

  • Static ( antype,STATIC)

  • Harmonic ( antype,HARMIC) – full, VT [ OMEGA_FN_VT_KRY ], Krylov [ OMEGA_FN_VT_KRY ], or mode-superposition [ OMEGA_mode-sup_LoadSupport ]

  • Transient ( antype,TRANS) – full or mode-superposition [ OMEGA_mode-sup_LoadSupport ]

  • Substructuring ( antype,SUBSTR)

  • Modal ( antype,MODAL)

Loads for VT and Krylov methods are supported as long as they are not:

  • complex tabulated loads (constant or trapezoidal loads in tabulated form are supported)

  • used in conjunction with Rotordynamics ( coriolis,on).

In a mode-superposition harmonic or transient analysis, you must apply the load in the modal portion of the analysis. Mechanical APDL calculates a load vector and writes it to the MODE file, which you can apply via the lvscale command.

The command supports tabular boundary conditions (TABNAME_X, TABNAME_Y, and TABNAME_Z) for OMEGA_X, OMEGA_Y, and OMEGA_Z input values ( dim ) for full transient and harmonic analyses.

Rotational velocities are combined with the element mass matrices to form a body-force load vector term. Units are radians/time. Related commands are acel, cgloc, cgomga, dcgomg, and domega.

See Analysis Tools

If you have applied the Coriolis effect ( coriolis ) using a stationary reference frame, this command takes the gyroscopic damping matrix into account for the elements listed in the Stationary Reference Frame heading in the notes section of the coriolis command. The element axis must pass through the global Cartesian origin. The program verifies that the rotation vector axis is parallel to the axis of the element; if not, the gyroscopic effect is not applied. After issuing omega when the Coriolis or gyroscopic effect is present, a subsequently issued cmomega command has no effect.

The load interpolation setting ( kbc ) applies to the rotational velocity, in particular the OMGSQRDKEY option for quadratic interpolation.

This command is also valid in PREP7.