ROTORG

Bulk Data Entry

ROTORG – Grids for the Rotor Line Model (Rotor Dynamics).

Description

This Bulk Data Entry is used for the specification of grids that determine the Rotor Line model.

Format

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

Alternate Format

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

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

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

Argument	Options		Description
ROTORID	<INTEGER > 0>	setid:	The identification number of a rotor.

GRIDi	<INTEGER > 0> No default	List of grids that define the rotor line model.

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 Rotor Line model; 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.

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.