ROTORG

Bulk Data Entry 1D rotor definition. Specifies grids that determine the Rotor Line model.

Format

(1) (2) (3) (4) (5) (6) (7) (8) (9) (10)
ROTORG ROTORID GRID1 GRID2 etc. GRIDn

Alternate Format

(1) (2) (3) (4) (5) (6) (7) (8) (9) (10)
ROTORG ROTORID GRID1 THRU GRID2

Example

(1) (2) (3) (4) (5) (6) (7) (8) (9) (10)
ROTORG 25 2345 2356 2400 2450

Example (Alternate Format)

(1) (2) (3) (4) (5) (6) (7) (8) (9) (10)
ROTORG 30 2300 THRU 2400

Definitions

Field Contents SI Unit Example
ROTORID
setid
The identification number of a rotor.

<INTEGER > 0>

GRIDi List of grids that define the rotor line model.

No default <INTEGER > 0>

THRU (optional) Flag indicating that a range of grid identification numbers is defined. The initial and final grids are specified on the fields either side of the field containing the THRU flag.

Comments

  1. All grid point entries specified on the ROTORG entry must be unique. The program will run into an error, if duplicate grid entries are specified.
  2. Multiple ROTORG entries can be defined with the same ROTORID.
  3. This ROTORG entry is used to define a 1D rotor; therefore, for a specific ROTORID, all grids specified on the ROTORG entry must be collinear. OptiStruct automatically checks if the grids are collinear during a run.
  4. Rotors in frequency response and complex eigenvalue solutions can be replaced using superelements. Superelements can be attached to the grids that define the rotor in the ROTORG Bulk Data Entry. Craig-Bampton Nodal Formulation (CBN) or Guyan Reduction (GUYAN) can be specified on the METHOD field in the CMSMETH Bulk Data Entry to generate the superelements. The superelement replaces the beam elements used to model the rotor. The ASET grid points should correspond to the GRIDi points specified on the ROTORG Bulk Data Entry. The interface grid points of the superelement used to model the rotor should be exactly the same grid points defined on the ROTORG entry. The General Modal Formulation (GM method) cannot be used to generate superelements for Rotor dynamics.
  5. If superelements are not used, connections between grids in the Rotor Line model and those not listed on the ROTORG entry must be defined using MPC's or rigid elements.
  6. If superelements are used, connections between grids in the Rotor Line model and those in the residual structure must be defined using MPC's or rigid elements.
  7. The mass of the Rotor Line model should be defined on the grids defined on the grids specified by the ROTORG Bulk Data Entry.
  8. The ROTOR Bulk Data Entry can be used to define 3D rotor models.
  9. For more information, refer to Rotor Dynamics in the User Guide.